Cheap flights from Illinois to London from £203

The cheapest month to fly to London from Illinois is in February. Flight prices, which tend to average around £481, are often lower during this time because this is during the off-season. The month of September is another great option to travel to London, with average flight prices from Illinois averaging around £482.

Our data shows that Sunday is the least expensive day to fly to London. Tickets to fly out on this day can be as low as £511. When flying out on a Friday, the most expensive travel day of the week, you can expect to see flight prices from Illinois to London for around £674.

The cheapest time of day to fly to London is in the evening when flights can be purchased for as low as £571. Flights in the afternoon are often more expensive, with an average ticket price of £612.

Fly from Chicago O'Hare Intl to London Heathrow for the best Illinois - London flight prices

You are more likely to see cheaper flights to London from Illinois when booking weeks ahead of your departure date. In general, you can expect to find flights to London for around £586 when searching weeks before you fly. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to London from Illinois for as low as £530 on momondo.

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

Icelandair, British Airways, and United Airlines are the most popular carriers operating from Illinois to London

British Airways, Aer Lingus and Iberia are the top three most popular airlines that fly to London from Illinois according to our data. British Airways is the first choice among our users, with 58% of people opting to fly with this airline when travelling to London. Keep in mind that there are 7 different airlines that fly to London on a routine basis, so you have a few additional options to choose from.

As of March 2026, 44 flights take off from Illinois and land in London each day. The most common flight departure time for this route is 17:00, with 60% of daily flights taking off in the evening.

As of March 2026, 309 flights take off from Illinois and land in London each week. The most common flight departure day for this route is Wed, with 15% of weekly flights taking off on this day.