$79 Find Cheap Flights from Seattle to Illinois

This is the cheapest one-way flight price found by a KAYAK user in the last 72 hours by searching for a flight from Seattle to Illinois departing on 2/22. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
1 adult
1 adult, Economy, 0 bags

KAYAK searches hundreds of travel sites at once for deals on flights to Illinois

 
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Seattle to Illinois.
These are the airlines KAYAK users have selected most often from within our search results in flight searches from Seattle to Illinois.
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Cheap Flights from Seattle to Illinois

Cheapest round-trip prices found by our users on KAYAK in the last 72 hours
Chicago
Chicago1 stop$173
Moline
Moline1 stop$309
Peoria
Peoria1 stop$280
Bloomington
Bloomington1 stop$315
Champaign
Champaign1 stop$268
St. Louis
St. Louis2 stops$157
Decatur
Decatur1 stop$425
Paducah
Paducah1 stop$496
Chicago
Chicago1 stop$173
Moline
Moline1 stop$309
Peoria
Peoria1 stop$280
Bloomington
Bloomington1 stop$315
Champaign
Champaign1 stop$268
St. Louis
St. Louis2 stops$157
Decatur
Decatur1 stop$425
Paducah
Paducah1 stop$496

Book Cheap Seattle to Illinois Plane Tickets

 
Here are some of the best deals found on KAYAK recently from the most popular airlines for round-trip flights from Seattle to Illinois that are departing in the next months. While these flights were available on KAYAK in the last 72 hours, prices and availability are subject to change and deals may expire.
Discover the best prices for you by selecting your travel dates on KAYAK.

Recent round-trip flight deals from Seattle to Illinois

Tue, Feb 24 - Mon, Mar 2
Frontier Logo
6:30 pm - 3:53 pm
SEA
-
STL
19h 23m
2 stops
Frontier Logo
10:11 pm - 6:18 pm
STL
-
SEA
22h 07m
1 stop
$157Frontier
Tue, Feb 24 - Sat, Feb 28
American Airlines Logo
12:07 am - 10:03 am
SEA
-
STL
7h 56m
1 stop
American Airlines Logo
6:36 pm - 12:24 am
STL
-
SEA
7h 48m
1 stop
$159American Airlines
Wed, Apr 8 - Wed, Apr 22
Delta Logo
5:30 am - 1:17 pm
SEA
-
STL
5h 47m
1 stop
Delta Logo
6:45 pm - 11:59 pm
STL
-
SEA
7h 14m
1 stop
$177Delta
Sun, Mar 1 - Wed, Apr 1
Southwest Logo
7:25 am - 1:30 pm
SEA
-
MDW
4h 05mnonstop
Southwest Logo
9:20 pm - 11:55 pm
MDW
-
SEA
4h 35mnonstop
$177Southwest
Sat, Feb 28 - Sun, Mar 22
Southwest Logo
7:05 am - 1:10 pm
SEA
-
MDW
4h 05mnonstop
Southwest Logo
9:45 pm - 12:20 am
MDW
-
SEA
4h 35mnonstop
$179Southwest
Sat, Feb 21 - Wed, Feb 25
United Airlines Logo
12:32 pm - 11:26 pm
SEA
-
ORD
8h 54m
1 stop
United Airlines Logo
4:20 pm - 7:03 pm
ORD
-
SEA
4h 43mnonstop
$183United Airlines
Wed, Apr 8 - Wed, Apr 22
Alaska Airlines Logo
6:02 pm - 11:59 pm
SEA
-
STL
3h 57mnonstop
Alaska Airlines Logo
7:00 am - 9:32 am
STL
-
SEA
4h 32mnonstop
$197Alaska Airlines
Thu, Mar 26 - Mon, Mar 30
Delta Logo
1:32 pm - 12:21 am
SEA
-
STL
8h 49m
1 stop
Delta Logo
6:12 pm - 12:03 am
STL
-
SEA
7h 51m
1 stop
$198Delta
Tue, Feb 24 - Mon, Mar 2
Alaska Airlines Logo
7:55 am - 1:51 pm
SEA
-
STL
3h 56mnonstop
Alaska Airlines Logo
7:00 am - 9:42 am
STL
-
SEA
4h 42mnonstop
$207Alaska Airlines
Fri, Feb 27 - Wed, Mar 4
United Airlines Logo
11:59 pm - 10:11 am
SEA
-
PIA
8h 12m
1 stop
United Airlines Logo
5:25 pm - 10:43 pm
PIA
-
SEA
7h 18m
1 stop
$280United Airlines
Booking Insights

KAYAK's insights & trends for Seattle to Illinois flights

Get data-powered insights and trends into flights from Seattle to Illinois to help you find the cheapest flights, the best time to fly and much more.

What is the cheapest Seattle to Illinois flight route?

Data is based on round-trip flight searches on KAYAK over the past month.

The cheapest ticket to Illinois from Seattle found in the last 72 hours was to Chicago, at $176 round-trip. The most popular route is from Seattle (SEA) to Chicago O'Hare Intl Airport (ORD), and the cheapest round-trip airline ticket found on this route in the last 72 hours was $176.

Can I save money by flying with a layover from Seattle to Illinois?

The average round-trip price for all non-stop flights, flights with one layover, and flights with two layovers for the route found by users searching on KAYAK in the last 2 weeks.

No, with an average price for the route of $286, prices are generally cheapest when you fly direct.

What is the cheapest month to fly from Seattle to Illinois?

To calculate monthly average prices, KAYAK takes all prices for each month over the last year for round-trip flights from Seattle to Illinois, removes the top 0.1% to account for outliers, and then takes the median of all values for each month.

The cheapest month for flights from Seattle to Illinois is February, when tickets cost $245 (return) on average. On the other hand, the most expensive months are December and June, when the average cost of round-trip tickets is $367 and $329 respectively.

What’s the cheapest day of the week to fly from Seattle to Illinois?

The average price of all round-trip flights from Seattle to Illinois clicked on KAYAK for each day over the last 12 months.

For Seattle to Illinois, Wednesday is the cheapest day to fly on average and Sunday is the most expensive. Flying from Illinois back to Seattle, the best deals are generally found on Wednesday, with Monday being the most expensive.

How far in advance should I book a flight from Seattle to Illinois?

To calculate weekly average prices, KAYAK takes all prices for each week before departure over the last year for round-trip flights from Seattle to Illinois, removes the top 0.1% to account for outliers, and then takes the average of all the values for each week.

To get a below average price on the flight from Seattle to Illinois, you should book around 3 weeks before departure, which saves you about 47% compared to booking last minute. For the absolute cheapest price, our data suggests you should book 10 weeks before departure.

Good to know

Low seasonJanuary
Cheapest flight$77
Best time to beat the crowds with an average 16% drop in price.
Most popular time to fly with an average 11% increase in price.
Flight from Seattle to St. Louis

FAQs - booking Illinois flights

  • How does KAYAK find such low prices on flights from Seattle to Illinois?

    KAYAK is a travel search engine. That means we look across the web to find the best prices we can find for our users. With over 2 billion flight queries processed yearly, we are able to display a variety of prices and options on flights from Seattle to Illinois.

  • How does KAYAK's flight Price Forecast tool help me choose the right time to buy my flight ticket from Seattle to Illinois?

    KAYAK’s flight Price Forecast tool uses historical data to determine whether the price for a flight from Seattle to Illinois is likely to change within 7 days, so travelers know whether to wait or book now.

  • What is the Hacker Fare option on flights from Seattle to Illinois?

    Hacker Fares allow you to combine one-way tickets in order to save you money over a traditional round-trip ticket. You could then fly from Seattle to Illinois with an airline and back with another airline.

  • What is KAYAK's "flexible dates" feature and why should I care when looking for a flight from Seattle to Illinois?

    Sometimes travel dates aren't set in stone. If your preferred travel dates have some wiggle room, flexible dates will show you all the options when flying from Seattle to Illinois up to 3 days before/after your preferred dates. You can then pick the flights that suit you best.

  • What is the cheapest time of day to fly to Illinois?

    The cheapest time of day to fly to Illinois is generally in the evening, when round-trip flights cost $292 on average. Morning departures are around 51% more expensive than evening flights, on average. The most expensive time of day to fly to Illinois is generally in the morning, which is peak travel time and where the average cost of a ticket is $441.

Top tips for finding cheap flights to Illinois

  • Looking for a cheap flight? 25% of our users found tickets from Seattle to the following destinations at these prices or less: Chicago $178 one-way - $288 round-trip

Reviews of the top 5 airlines serving from Seattle to Illinois

 
See real verified KAYAK customer reviews for airlines flying from Seattle to Illinois. Airline scores are aggregated from all reviews left by passengers on KAYAK after flying with an airline. KAYAK doesn’t show reviews that are older than 5 years. Learn how KAYAK collects reviews.
Need help choosing which airline to fly with from Seattle to Illinois? KAYAK airline reviews give an overall score for each airline based on loads of factors, including comfort, boarding, in-flight entertainment and more, to make your decision easier. See airline scores according to verified KAYAK customer reviews.
8.0
Alaska AirlinesOverall score based on 11801 reviews
8.1Boarding
7.1Food
7.0Entertainment
7.8Comfort
8.5Crew
Airline reviews

There is nothing critical to complain about but I would say the snacks are pretty bad Airline staff could be aggressive the way they move through the aisles and the plane I also got hustled for a small wallet size men bag and force the consolidated with my carry on item we're talking about a wallet size bag.

6.0 Goodrsmrostov, Jan 2026
SEA - BOS
Read more Alaska Airlines reviews

There is nothing critical to complain about but I would say the snacks are pretty bad Airline staff could be aggressive the way they move through the aisles and the plane I also got hustled for a small wallet size men bag and force the consolidated with my carry on item we're talking about a wallet size bag.

Departed on time and had an efficient boarding process. The inflight wifi was not working on one of the flights.

How can I review what was denied to me. Instead of offering to let me pay for the ticket I got booted of my flight with no way home and no choice but to purchase another ticket for 12 hours later. Filing a complaint with the DOT

From Las Vegas to Boise all went well. However, our flight was delayed in Boise and I missed my connecting flight from Seattle to Pasco. Moreover, the last flight to Pasco was full and I was booked on the 11:30 flight Sunday and given a hotel accommodation. However, I was scheduled to deliver the Sunday morning service at my church and needed to arrive no later than 10:00. Therefore, I booked a Delta flight scheduled to arrive in Pasco at 23:09. My piece of luggage checked in Las Vegas arrived in Pasco earlier today. I waited at the airport for over an hour last night to speak with an Alaska agent to no avail. I went back after church this morning in search of my piece of luggage and it could not be located. After waiting for 40 minutes to speak to the agent authorized to take my claim, he announced that he was closing the counter to assist on the flight line but not before providing me with a telephone number that would help me with filing my claim. Before I was able to make the call (due to other factors) I received a call from Alaska agent informing me that my luggage had just arrived and I am now waiting for it to be delivered. I deliberately took the more complicated route home to ensure that I would be home in plenty of time to prepare for myself for the Sunday service and accommodate my relatives’ needs. I believe the airport is undermanned given the number of flights coming in and going out. It was fiasco last night with three flights waiting for luggage and another flight landing within minutes. Today’s problems stemmed from a lack of cross training and a serious amount of cargo/baggage going out and too few people scheduled to cover.

The cabin crew was absolutely wonderful, the service was great and it was just a good flight overall.

I like them since I live in Alaska and I don't have much choice

The flight attendants were nice, but the cabin and seats were uncomfortable.

Food was terrible, noisy plane & would never pay to fly first class again. Seats in regular price are too small, no leg room & center aisle much too, too small. Seats in 1st class larger but not comfortable.

Overall, once we took off, our flight was good. Flight departure was significantly delayed due to mechanical issues. Upon arrival, it took wayyy too long to retrieve checked bags.

The ticket I purchased through Kayak did not show up in my Alaska Airlines app, and neither of the codes given to me worked for online check in. I've never had to show up to the airport at 6am wondering if I've been scammed. Cheap flight fare or whatever does not play well with airlines and I will be wary of using Kayak in the future.

delta last minute gave me a boarding pass for a different flight with no confirmation that they were changing it

The service from the flight attendants were of supreme quality. They greeted and treated everyone with a wide smile. This is totally absent nowadays. Kudos to them!!!!

Excellent flight and got us around tough weather. Only issue was seat TV did not work and crew tried to reboot.

Very large passenger too space from my own seat. Arm board couldn’t be lowered because of his size. It wads very uncomfortable trip, as the flight was full couldn’t move anywhere having back pain because of the position in which I was the entire flight.

was sitting in the jet bridge for 10 minutes in -20 degree weather waiting for my bag

Outdated equipment in disrepair, wifi inoperable. Broken seats, taped air vents, generally poor condition, the 717 showed its age and lack of upkeep.

My flight out of Baton Rouge to Atlanta was delayed by a half hour. This got us into Atlanta airport 30 minutes late. I ran through the airport to get to my connecting flight. As I approached the boarding gate, I saw the boarding door was still open and a passenger was being checked in. But when I got to the gate, the boarding agent told me they had already given away my seat and there were no empty seats on that flight. So I had to take a later flight. That has never happened to me before. Very frustrating.

Connection through Atlanta was difficult. Mechanical issue on plane caused a two hour delay. New gate was a mile away.

No WiFi. Comfort plus should have alcohol provided, crew only offered water or tea. Who the heck wants tea?

The flight was delayed and oversold. I volunteered to give up my seat for compensation. Thinking I could get a good night's sleep instead of arriving home at 2 am. It took over an hour to get the new reservation confirmed, three different gate attendants, and two red coats. It took even longer to confirm the overnight hotel, and when I arrived, the line was 45 minutes long, with two people checking in, and at least 15 people slowly, very slowly—no food except frozen convenience food, no coupon for food from airlines. Slept, headed back to the airport, and that flight had an equipment change and a gate change just as they were about to board. It took an additional hour to board as they cleaned the plane from storage.

Yall need to integrate your system with Alaska more efficiently. They booted me off the first flight because of a discrepancy on your end.

The crew at Hawaiian Airlines was fantastic. Kind and hard working. The pilots were great with giving us all the updates to make sure we were informed.

Very good. Nice plane and we sat in economy plus - bigger seats, more room. They served a meal and snacks, and the meal was an apple stuffed pancake that was very good! The snack for us was a hummus sandwich - also very good. The flight attendants were helpful and nice. They have plenty of movies and shows to watch. My only negative -- they changed our flights around and did not adjust the layovers, so we ended up with a very long and unnecessary layover in Honolulu.

I liked the Starlink WiFi but didn't like how they said they were the only airline to offer a free meal and it turns out to be just a standalone sandwich and then charge for snacks to go with it. Rather have the free snacks like Southwest, but have the option to purchase a decent meal for a 5+ hour flight.

Flight scheduled to take off at 5.55pm but it did not take off until 7pm due to some food delivery delay.

Unfortunately, I was put into the middle seat in the first row of premium seating. Sounds nice right? No! that is the worst seat in the plane. I wish I was in economy rather than be in that seat! There is no seat back pocket, no tray table, no charger. Nothing! so unless you're row mates are willing to let you share their basic amenities any flyer should have, you are stuck. It was the worst experience ever! And the flight attendant forgot to take my drink order. I felt like the forgotten flyer.

Delayed and cancelled flights were hard and very stressful, both ways!

The crew was quite good, they came by often with drinks or to collect trash. But what wasn't nice was the flight was over weigh and several people had to be rebooked. I was questioned whether I should have a seat when I was getting to it. The in-flight entertainment kept buffering and interrupting. And the route took the airplane through high winds which caused us a longer flight

Wasn’t on the flight due to Alaska cancellation…also after all the rerouting, I was going to be on a later flight that left SFO at 7:47pm, which meant an almost 6 hour layover. That same Hawaiian flight was delayed for another 2hours.

I had to cancel the flight because with a 3 hour delay for 'unexpected maintenance' in getting to LAX, I couldn't connect to an overseas flight that I had booked on Scandinavian Air.

Seated dude next to me even though lots of empty rows. But main thing was we sat on the tarmac after landing for 30 minutes because of, in the words of the dude who sat next to me, “operational incompetence”. We got changing directions about where to pick up gate checked bags. Pilot and flight attendant were awesome though.

It was a pretty standard flight... until the almost hour and a half spent on the taxi way. I get that the weather has been poor but the delay had nothing to do with the weather and more to do with a plane with several issues tying up the gate. I get that that happens from time to time but this has been EVERY flight I've been on for the past 5 years and I fly 3 to 5 times a year. This isn't just United... it's American, it's Delta. It's an issue with the entire industry. I work for UPS and packages on a cargo plane get better service than people do these days. Anymore I HATE flying.

Perfect flight. Smooth flight. Arrived 20 minutes early at destination. Excellent service.

The flights were on time which was great give. It was holiday travel season and there’d been some weather issues. The only complaint and this is every time with United is the terrible seat design. The head rest is not built for comfort and having my neck bent forward for a cross country trip reminded me while I try not to take United flights as a rule.

Everything was absolutely wonderful from check in to baggage claim. Staff was very professional and sweet. Will definitely recommend United to family and friends.

They did the one thing that really matters - got to Chicago early.

The flight was on time. I generally don’t drink or eat on short flights and the seats were good and the flight attendants were friendly. That’s all I expect

It was nice to have gotten up upgraded to first class with a meal on a three hour flight

Very bad! They kept delaying my flight and wouldn’t do anything about it

Door to door, the crew and staff were amazing. It was a stressful travel day with delays, but they were focused on customers and doing what they could to get us to our destinations.

Pilot navigated severe weather/snow storm with skill. Described his intentions clearly

Little warm on the plane and delayed for an hour

So excited very proud first of all I wanna thank kayak all updates very professional and fast alart And amazing cabin crew so nice to me they deserve big salute

The boarding process needs to be fixed. The zone don't work, especially when there is hardly anyone in zones 3, 4,and 5, leaving the majority of the passengers backed up in the aisle, especially because passengers seated near the front are blocking passengers who are seated in the rear of the plane. It would also help if the size of carry on bags was more strictly enforced.

Great flight - friendly and attentive team! Seats in coach were comfy, but a little cramped - but that is the case with all airlines ;)

Awful. They won’t help me with anything. I booked on American but they abdicated to Iberia. The ticket was overpriced. Everything negative

I enjoyed the extra leg room compared to other airlines. The first stewards made my daughter’s birthday special by giving her an extra snack. Then the last one coming home from Chicago to Appleton made our night really enjoyable Thanks for making our trip enjoyable

It was good..clean, comfy seat. Friendly warm welcoming crew. Was able to check my cabin luggage at the gate which I was able to pickup in a decent time from baggage claim. The app gave all updates from delays to baggage claim info. Overall smooth flight.

It was a typical flight. We had a delay which seems to be the normality now. And we had no in flight service due to conditions.

After we landed we sat on the tarmac for 1.5 hours waiting to get to our gate. Ridiculous.

Everything you need to know for your flight from Seattle to Illinois

Information on your arrival and departure airports