The cheapest Oslo to Chicago return flight on the radar right now is €354, flying with Icelandair via one or more connections. It covers departures in February 2027, and every dated link below opens that exact OSL–ORD search on Skyscanner. At 32% under the €523 we normally record here, it is one of the strongest OSL–ORD fares in our index. Across 85 recorded checks it has ranged between €339 and €1,001. Our sampling points to February 2027 as the cheapest month to fly Oslo to Chicago.
Every fare here is re-confirmed against Skyscanner automatically, and each one is stamped with the moment it was last checked, so you can see how fresh it is instead of taking it on trust. Not flying from Oslo? We track 61 other departure cities for Chicago, listed at the foot of this page.
Fares move quickly. If this Oslo to Chicago price has gone by the time you search, shift the dates a day or two either side, because the same route is often still cheap just next door.