AirHint found the following cheapest return flights from Boston (BOS) to Lisbon (LIS) in December 2025 (see full year).

Return flights

02 Dec - 09 Dec	TAP	direct
18 Dec - 23 Dec	British Airways
17 Dec - 24 Dec	Iberia
12 Dec - 19 Dec	TAP	direct
05 Dec - 12 Dec	Delta	direct
20 Dec - 30 Dec	Iberia For Level
21 Dec - 02 Jan	Iberia For Level
26 Dec - 04 Jan	Icelandair
19 Dec - 28 Dec	Iberia
22 Dec - 29 Dec	United
17 Dec - 24 Dec	Air France	direct
20 Dec - 30 Dec	Air France	direct
19 Dec - 02 Jan	Aer Lingus
19 Dec - 04 Jan	Azores Airlines

Also check the deals for one-way flights from Boston to Lisbon 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.

Book a cheap hotel in Lisbon

Cheap car rent in Lisbon

Cheapest return flights from Boston to Lisbon in December from $489

Return flights