AirHint found the following cheapest return flights from London (LCY) to Oslo (OSL) in September 2025 (see full year).

Return flights

26 Sep - 30 Sep	KLM
03 Sep - 10 Sep	KLM
01 Sep - 09 Sep	KLM
15 Sep - 22 Sep	KLM
04 Sep - 09 Sep	KLM
16 Sep - 23 Sep	KLM
17 Sep - 22 Sep	KLM
18 Sep - 22 Sep	KLM
03 Sep - 09 Sep	KLM
10 Sep - 24 Sep	KLM
26 Sep - 01 Oct	KLM
30 Sep - 05 Oct	KLM
29 Sep - 08 Oct	KLM
23 Sep - 02 Oct	KLM
24 Sep - 01 Oct	KLM
27 Sep - 05 Oct	KLM
01 Sep - 02 Oct	KLM
24 Sep - 08 Oct	KLM
26 Sep - 06 Oct	KLM
30 Sep - 01 Oct	KLM

Also check the deals for one-way flights from London to Oslo in September.

The deals are updated regularly. The prices may go up as tickets are purchased by other travellers. Only the cheapest flights are offered. Select a price to book and secure these cheap prices.

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Cheapest return flights from London to Oslo in September from 183€

Return flights