AirHint found the following cheapest return flights from Seattle (SEA) to Mexico City (MEX) in December 2025 (see full year).

Return flights

09 Dec - 12 Jan	Hawaiian Airlines
01 Dec - 06 Dec	Hawaiian Airlines
11 Dec - 16 Dec	Hawaiian Airlines
31 Dec - 08 Jan	Alaska Airlines
27 Dec - 04 Jan	Alaska Airlines
23 Dec - 02 Jan	Alaska Airlines
20 Dec - 02 Jan	Alaska Airlines
23 Dec - 02 Jan	Delta	direct
27 Dec - 04 Jan	Delta	direct
20 Dec - 02 Jan	Delta	direct

Also check the deals for one-way flights from Seattle to Mexico City in December.

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 Seattle to Mexico City in December from 383€

Return flights