It will debut Seattle to London and Reykjavik flights.
Alaska plans to fly daily between Seattle and London Heathrow Airport on Boeing Dreamliner jets.
The Seattle-Reykjavik route will be flown on Boeing Max 8 jets as a seasonal spring and summer service.
The carrier has also announced plans for long haul flights to Rome and begins flights to Seoul, South Korea next month.
It said it hopes to have about a dozen long haul routes in operation from Sea-Tac soon.
The airline recently launched Tokyo flights from its west coast hub.
The airline also unveiled new livery for its Boeing Dreamliners with a bright new paint scheme.