AirHint found the following cheapest return flights from London (LHR) to Cancun (CUN) in September 2025 (see full year).

Return flights

25 Sep - 02 Oct	SWISS
24 Sep - 01 Oct	Air Canada
29 Sep - 08 Oct	Air Canada
19 Sep - 28 Sep	SWISS
10 Sep - 22 Sep	Air Canada
06 Sep - 12 Oct	Air Canada
22 Sep - 30 Sep	Air Canada
17 Sep - 02 Oct	Air Canada
02 Sep - 16 Sep	Air Canada
29 Sep - 13 Oct	Air Canada
29 Sep - 07 Oct	Air Canada
20 Sep - 23 Sep	SWISS
20 Sep - 27 Sep	SWISS
20 Sep - 24 Sep	SWISS
20 Sep - 30 Sep	SWISS
06 Sep - 11 Oct	Air Canada
22 Sep - 28 Sep	Air Canada
10 Sep - 14 Sep	Air Canada
27 Sep - 01 Oct	Air Canada
28 Sep - 07 Oct	Air Canada

Also check the deals for one-way flights from London to Cancun 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 Cancun in September from $639

Return flights