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

Return flights

09 Sep - 23 Sep	SWISS
11 Sep - 23 Sep	SWISS
09 Sep - 25 Sep	SWISS
02 Sep - 16 Sep	SWISS
02 Sep - 10 Sep	SWISS
04 Sep - 10 Sep	SWISS
27 Sep - 11 Oct	KLM
20 Sep - 04 Oct	KLM
05 Sep - 25 Sep	Delta
09 Sep - 22 Sep	Delta
10 Sep - 21 Sep	Delta
12 Sep - 21 Sep	Delta
19 Sep - 04 Oct	KLM
29 Sep - 14 Oct	KLM
21 Sep - 05 Oct	Delta
21 Sep - 01 Oct	Delta

Also check the deals for one-way flights from London to San Jose 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 San Jose in September from $829

Return flights