Flights to Jersey and Southampton will be offered by the Guernsey-based airline, Aurigny from May 2019.
A twice-daily return service will be offered to islanders travelling to both destinations.
Aurigny claims it will help them meet the target Guernsey States has given them to break even.
In 2017, Aurigny made a loss of £5.19 million. The airline's 2018 financial performance isn't known.
The airline spoke of possibly adding another route to its service in the future.
The announcement comes after Aurigny said Flybe's flights to Heathrow would have a "detrimental financial impact" and will likely lead to a loss of passengers on its Gatwick route.
The new Southampton and Jersey routes have been "worked on for many months" and have only recently been approved, according to the airline's Chief Executive.
Full schedules will be available for booking on Friday 1st March 2019.