AirHint found the following cheapest return flights from London (LCY) to Porto (OPO) in August 2025 (see full year).

Return flights

26 Aug - 04 Sep	KLM
28 Aug - 04 Sep	KLM
26 Aug - 05 Sep	KLM
27 Aug - 04 Sep	KLM
27 Aug - 03 Sep	KLM
19 Aug - 03 Sep	KLM
27 Aug - 30 Sep	KLM
28 Aug - 03 Sep	KLM
25 Aug - 03 Sep	KLM
19 Aug - 05 Sep	KLM
20 Aug - 28 Aug	KLM
25 Aug - 28 Aug	KLM
19 Aug - 26 Aug	KLM
21 Aug - 26 Aug	KLM
25 Aug - 29 Aug	KLM
18 Aug - 28 Aug	KLM
26 Aug - 28 Aug	KLM
21 Aug - 27 Aug	KLM
19 Aug - 25 Aug	KLM
18 Aug - 26 Aug	KLM

Also check the deals for one-way flights from London to Porto in August.

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 Porto in August from 246€

Return flights