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Cheap flights from Seattle to Illinois from $140

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from Seattle to Illinois departing on 7/8. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.
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0 bags

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Find the cheapest flights from Seattle to Illinois

Cheap round-trip flights

Enter your travel dates to find the best prices.
Frontier Logo
3:33 pm - 8:43 pm
SEA
-
ORD
27h 10m
1 stop
Frontier Logo
7:20 am - 10:35 am
ORD
-
SEA
29h 15m
1 stop
$294Frontier
Wed, Jul 1 - Fri, Jul 3
Frontier Logo
10:34 am - 6:17 am
SEA
-
ORD
17h 43m
1 stop
Frontier Logo
9:13 pm - 5:51 pm
ORD
-
SEA
22h 38m
1 stop
$295Frontier
Thu, Jul 9 - Thu, Jul 16
American Airlines Logo
5:00 am - 4:19 pm
SEA
-
BMI
9h 19m
1 stop
American Airlines Logo
5:00 am - 10:08 am
BMI
-
SEA
7h 08m
1 stop
$346American Airlines
Thu, Aug 13 - Sat, Aug 15
Delta Logo
11:59 pm - 10:25 am
SEA
-
MLI
8h 26m
1 stop
Delta Logo
5:09 pm - 11:57 pm
MLI
-
SEA
8h 48m
1 stop
$349Delta
Wed, Aug 26 - Sun, Aug 30
Delta Logo
11:59 pm - 10:25 am
SEA
-
MLI
8h 26m
1 stop
Delta Logo
11:08 am - 11:54 pm
MLI
-
SEA
14h 46m
2 stops
$354Delta
Wed, Aug 26 - Sun, Aug 30
Southwest Logo
11:05 pm - 5:00 am
SEA
-
MDW
3h 55mnonstop
Southwest Logo
10:00 pm - 12:30 am
MDW
-
SEA
4h 30mnonstop
$355Southwest
Fri, Jun 12 - Mon, Jun 15
United Airlines Logo
7:00 am - 3:38 pm
SEA
-
STL
6h 38m
1 stop
United Airlines Logo
5:10 am - 10:01 am
STL
-
SEA
6h 51m
1 stop
$357United Airlines
Fri, Aug 28 - Sun, Aug 30
American Airlines Logo
1:58 pm - 11:34 pm
SEA
-
PIA
7h 36m
1 stop
American Airlines Logo
4:27 pm - 10:59 pm
PIA
-
SEA
8h 32m
1 stop
$361American Airlines
Tue, Jun 9 - Sat, Jun 13
Southwest Logo
2:00 pm - 11:10 pm
SEA
-
MDW
7h 10m
1 stop
Southwest Logo
9:50 pm - 12:25 am
MDW
-
SEA
4h 35mnonstop
$361Southwest
Tue, Jul 14 - Wed, Jul 22
United Airlines Logo
1:56 pm - 10:58 pm
SEA
-
PIA
7h 02m
1 stop
United Airlines Logo
4:35 pm - 10:56 pm
PIA
-
SEA
8h 21m
1 stop
$371United Airlines
Tue, Sep 29 - Sat, Oct 3

Frontier flights from Seattle to Illinois

Our best Frontier deals on Seattle to Illinois flight tickets
Frontier
Jul 1
SEA3:33 pmSeattle/Tacoma Intl
27h 10m
1 stop
ORD8:43 pmChicago O'Hare Intl
Jul 3
ORD7:20 amChicago O'Hare Intl
29h 15m
1 stop
SEA10:35 amSeattle/Tacoma Intl
$294
Frontier
Jul 9
SEA10:34 amSeattle/Tacoma Intl
17h 43m
1 stop
ORD6:17 amChicago O'Hare Intl
Jul 16
ORD9:13 pmChicago O'Hare Intl
22h 38m
1 stop
SEA5:51 pmSeattle/Tacoma Intl
$295
Frontier
Jun 6
SEA7:50 pmSeattle/Tacoma Intl
22h 42m
1 stop
ORD8:32 pmChicago O'Hare Intl
Jun 12
ORD9:48 pmChicago O'Hare Intl
14h 00m
1 stop
SEA9:48 amSeattle/Tacoma Intl
$296

Alaska Airlines flights from Seattle to Illinois

Our best Alaska Airlines deals on Seattle to Illinois flight tickets
Alaska Airlines
Jul 3
SEA12:17 amSeattle/Tacoma Intl
4h 03m
ORD6:20 amChicago O'Hare Intl
Jul 6
ORD8:20 pmChicago O'Hare Intl
4h 44m
SEA11:04 pmSeattle/Tacoma Intl
$332
Alaska Airlines
Jun 6
SEA12:09 amSeattle/Tacoma Intl
4h 11m
ORD6:20 amChicago O'Hare Intl
Jun 13
ORD8:05 pmChicago O'Hare Intl
4h 44m
SEA10:49 pmSeattle/Tacoma Intl
$343
Alaska Airlines
Jul 18
SEA10:29 amSeattle/Tacoma Intl
4h 15m
ORD4:44 pmChicago O'Hare Intl
Jul 18
ORD8:20 pmChicago O'Hare Intl
4h 44m
SEA11:04 pmSeattle/Tacoma Intl
$349

momondo Fare Finder

 
Customize your flight search to find flights from Seattle to Illinois that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, momondo users made 832,500 searches. Data last updated May 28, 2026.
Use the filters below to find and compare flights from Seattle to Illinois that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest round-trip

SeattleChicago

SEA - ORD

SEAORD

Seattle/Tacoma Intl

Wed 7/1

3:33 pm-8:43 pm

1 stop27h 10m

Chicago O'Hare Intl

Fri 7/3

7:20 am-10:35 am

1 stop29h 15m

$294

SeattleChicago

SEA - ORD

SEAORD

Seattle/Tacoma Intl

Thu 7/9

10:34 am-6:17 am

1 stop17h 43m

Chicago O'Hare Intl

Thu 7/16

9:13 pm-5:51 pm

1 stop22h 38m

$295

SeattleBloomington

SEA - BMI

SEABMI

Seattle/Tacoma Intl

Thu 8/13

5:00 am-4:19 pm

1 stop9h 19m

Bloomington-Normal

Sat 8/15

5:00 am-10:08 am

1 stop7h 08m

$346

SeattleMoline

SEA - MLI

SEAMLI

Seattle/Tacoma Intl

Wed 8/26

11:59 pm-10:25 am

1 stop8h 26m

Moline Quad-City

Sun 8/30

5:09 pm-11:57 pm

1 stop8h 48m

$349

SeattleMoline

SEA - MLI

SEAMLI

Seattle/Tacoma Intl

Wed 8/26

11:59 pm-10:25 am

1 stop8h 26m

Moline Quad-City

Sun 8/30

11:08 am-11:54 pm

2 stops14h 46m

$354
Quickest round-trip

SeattleChicago

SEA - MDW

SEAMDW

Seattle/Tacoma Intl

Fri 6/12

11:05 pm-5:00 am

Nonstop3h 55m

Chicago Midway

Mon 6/15

10:00 pm-12:30 am

Nonstop4h 30m

$355

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Fri 8/28

7:00 am-3:38 pm

1 stop6h 38m

Lambert-St Louis

Sun 8/30

5:10 am-10:01 am

1 stop6h 51m

$357

SeattlePeoria

SEA - PIA

SEAPIA

Seattle/Tacoma Intl

Tue 6/9

1:58 pm-11:34 pm

1 stop7h 36m

Greater Peoria

Sat 6/13

4:27 pm-10:59 pm

1 stop8h 32m

$361

SeattleChicago

SEA - MDW

SEAMDW

Seattle/Tacoma Intl

Tue 7/14

2:00 pm-11:10 pm

1 stop7h 10m

Chicago Midway

Wed 7/22

9:50 pm-12:25 am

Nonstop4h 35m

$361

SeattlePeoria

SEA - PIA

SEAPIA

Seattle/Tacoma Intl

Tue 9/29

1:56 pm-10:58 pm

1 stop7h 02m

Greater Peoria

Sat 10/3

4:35 pm-10:56 pm

1 stop8h 21m

$371

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 20 resultsSorted by cheapest first
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See travel insights to Illinois from

How to get the cheapest flight ticket from Seattle to Illinois

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

What is the cheapest month to fly to Illinois?

The cheapest month to fly to Illinois from Seattle is in January. Flight prices, which tend to average around $47, are often lower during this time because this is during the off-season. If you aren’t able to travel to Illinois during the month of January, then flying in February is also cheap. Prices for this month can be found on momondo for an average of $93.

What is the cheapest day to depart on your flight to Illinois?

The cheapest day to depart from Seattle to Illinois is on a Wednesday when prices can be found for as low as $411. Flights from Seattle to Illinois on a Sunday will generally be more expensive and average around $501. Keep in mind that these prices on both days could fluctuate depending on the season and the demand.

What is the cheapest time of day to depart on your flight to Illinois?

Our most recent data shows that the best time of day to fly to Illinois is in the afternoon. Flights from Seattle to Illinois during this time can be as low as $337. Flights in the morning are often more expensive with an average ticket price of $450.

What is the cheapest Seattle/Tacoma Intl to Illinois flight route?

Fly from Seattle/Tacoma Intl to Chicago O'Hare Intl for the best Seattle/Tacoma Intl - Illinois flight prices

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

You are more likely to see cheaper flights to Illinois from Seattle when booking weeks ahead of your departure date. In general, you can expect to find flights to Illinois for around $318 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Illinois from Seattle for as low as $267 on momondo.

What cabin class options are available on Seattle to Illinois flights?

There are 4 cabin classes available to choose from on Seattle to Illinois flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Can stopping save me money on Seattle to Illinois flights?

You could potentially save up to 50% on your flight if you consider stops on a Seattle to Illinois flight.

Cheap Seattle to Illinois flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from Seattle to Illinois

Best Price Found

$201

Fastest flight time

3h 50m

Direct flights

Every day

Airports in Illinois

98 airports
The best one-way flight to Illinois from Seattle in the past 72 hours is $201. The best round-trip flight deal from Seattle to Illinois found on momondo in the last 72 hours is $379.
The fastest flight from Seattle to Illinois takes 3h 50m
Direct flights go from Seattle to Illinois every day.
There are 98 airports in Illinois. From Seattle there are direct flights to Chicago Midway (MDW), Lambert-St Louis (STL).
Search flight deals

Frequently asked questions about flying from Seattle to Illinois

  • When did momondo last update prices for flights from Seattle/Tacoma Intl Airport to Illinois?

    Prices for flights from Seattle/Tacoma Intl Airport to Illinois are updated daily.

  • How many operators does momondo search for flights from Seattle/Tacoma Intl Airport to Illinois?

  • How old do you have to be to fly from Seattle/Tacoma Intl Airport to Illinois?

    The minimum age for a child to fly alone is five, but airlines offering an unaccompanied minor (UNMR) service may have their age restrictions, such as regulations concerning flight duration, timing, and layovers. It is recommended that you verify with the airline you are booking with for travel from Seattle/Tacoma Intl Airport to Illinois.

  • What documentation or ID do you need to fly to Illinois?

    The necessary travel and health documents for your Illinois trip may vary depending on your travel plans and individual circumstances. Generally, you should have various documents, such as a national ID card or driver's license and a passport that is valid for six months beyond your scheduled arrival date. We recommend seeking advice from your airline or a trusted third party, such as IATA.

  • What is the most popular plane model from Seattle to Illinois?

Best airlines flying from Seattle to Illinois

Compare and see reviews for airlines that fly from Seattle to Illinois with momondo
Airline
Rating
Free Cancellation
Price
DeltaPriceFrom $111Free CancellationRating
7.9
8,424 reviews
Search Delta flights
Hawaiian AirlinesPriceFrom $124Free CancellationRating
7.8
2,835 reviews
Search Hawaiian Airlines flights
Alaska AirlinesPriceFrom $177Free CancellationRating
7.9
12,422 reviews
Search Alaska Airlines flights
United AirlinesPriceFrom $177Free CancellationRating
7.4
9,751 reviews
Search United Airlines flights
American AirlinesPriceFrom $178Free CancellationRating
7.1
11,639 reviews
Search American Airlines flights
FrontierPriceFrom $193Free CancellationRating
5.6
2,932 reviews
Search Frontier flights
SouthwestPriceFrom $207Free CancellationRating
7.9
4,265 reviews
Search Southwest flights

Why use momondo?

Why should I use momondo to find a flight deal from Seattle to Illinois?

momondo compares prices from hundreds of airlines and agents so you can find and book the best deal on flights from Seattle to Illinois. Millions of users trust and use momondo every year so you are in good hands.

Can I find flights from Seattle to Illinois with flexible booking policies on momondo?

All flight searches from Seattle to Illinois on momondo can be filtered to show those which offer flexible booking policies.

How can momondo help me find flights from Seattle to Illinois?

Once all potential Seattle to Illinois flight options are in front of you, momondo lets you sort and filter flights based on preferences such as airline, price and flight times amongst many other options.

I’m not ready to book a flight from Seattle to Illinois right now. Can momondo alert me if prices change?

Price alerts on flights to Illinois from Seattle are quick and easy to set up on momondo. Simply perform a search and select the price alert feature. It is as simple as that.

An easier way to manage your Illinois trip

We make it super easy to schedule, organize and travel with friends or family. Trips is free — and available to use no matter where you book.
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Sat 6/27
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