AirHint found the following cheapest return flights from Bilbao (BIO) to Bucharest (OTP) in September 2025 (see full year).

Return flights

29 Sep - 07 Oct	Vueling Airlines
24 Sep - 01 Oct	Vueling Airlines
08 Sep - 14 Sep	Vueling Airlines
29 Sep - 02 Oct	Vueling Airlines
24 Sep - 28 Sep	Vueling Airlines
23 Sep - 30 Sep	Air Europa
17 Sep - 24 Sep	Vueling Airlines
26 Sep - 28 Sep	Wizz Air Malta
30 Sep - 11 Oct	Volotea
18 Sep - 22 Sep	Vueling Airlines
10 Sep - 15 Sep	Vueling Airlines
15 Sep - 20 Sep	Vueling Airlines
14 Sep - 16 Sep	easyJet
08 Sep - 15 Sep	Vueling Airlines
30 Sep - 03 Oct	Vueling Airlines
28 Sep - 04 Oct	Volotea
23 Sep - 03 Oct	Air Europa

Also check the deals for one-way flights from Bilbao to Bucharest 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 Bilbao to Bucharest in September from 90€

Return flights