AirHint found the following cheapest return flights from Denver (DEN) to San Jose (SJO) in December 2025 (see full year).

Return flights

05 Dec - 13 Dec	United
10 Dec - 19 Dec	Southwest Airlines
13 Dec - 20 Dec	United
12 Dec - 21 Dec	United
06 Dec - 20 Dec	United
12 Dec - 20 Dec	United
07 Dec - 12 Dec	Southwest Airlines
27 Dec - 10 Jan	Frontier Airlines
26 Dec - 10 Jan	Frontier Airlines
22 Dec - 10 Jan	Frontier Airlines
25 Dec - 04 Jan	Frontier Airlines
27 Dec - 04 Jan	Frontier Airlines
27 Dec - 10 Jan	Southwest Airlines	direct
18 Dec - 05 Jan	Frontier Airlines
19 Dec - 05 Jan	Frontier Airlines

Also check the deals for one-way flights from Denver to San Jose 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 Denver to San Jose in December from $285

Return flights