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

Return flights

23 Sep - 10 Oct	Norwegian	direct
30 Sep - 14 Oct	Norwegian	direct
25 Sep - 05 Oct	Ryanair
24 Sep - 26 Sep	Ryanair
29 Sep - 03 Oct	Wizz Air
16 Sep - 30 Sep	Ryanair
23 Sep - 26 Sep	Norwegian	direct
30 Sep - 17 Oct	Norwegian	direct
30 Sep - 10 Oct	Norwegian	direct
16 Sep - 21 Sep	Ryanair
30 Sep - 02 Oct	Norwegian
20 Sep - 21 Sep	Ryanair
21 Sep - 23 Sep	Norwegian	direct
28 Sep - 14 Oct	Norwegian	direct
19 Sep - 23 Sep	Ryanair
28 Sep - 17 Oct	Norwegian	direct
28 Sep - 07 Oct	Norwegian	direct
25 Sep - 29 Sep	Ryanair
19 Sep - 23 Sep	Norwegian	direct
25 Sep - 28 Sep	Ryanair

Also check the deals for one-way flights from Oslo to Brussels 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 Oslo to Brussels in September from 134€

Return flights