Regional airline Eastern Airways has reached an agreement to buy Air Southwest from its current owner.
Plymouth-based Air Southwest pulled out of London City airport in May, saying at the time it wanted to "refocus" on services to Gatwick.
Air Southwest, currently owned by Sutton Harbour Group, should become part of the Humberside-based Eastern Airlines by October this year.
Eastern Airlines plans to keep the Air Southwest brand, however, for routes into Plymouth, Newquay and Bristol.
In a statement from Eastern Airways, the airline said it plans to develop its business and expand its network in the south west of England.
Air Southwest, launched in 2003, currently operates from 12 airports using a fleet of five aircraft and employs 135 staff.
Richard Lake, managing director of Eastern Airways, said: "As market leaders in our respective catchments this deal makes perfect sense for Eastern Airways and gives us an even greater reach across the UK.
"The integration of the two airlines also enables greater operational flexibility and efficiency as we can look into synergies by bringing both networks and fleets closer together."
Nigel Godefroy, chief executive of Sutton Harbour Group, said: "Being part of a larger airline will bring stability to Air Southwest and that is good news for air travel to and from the far South West, and for Plymouth and Newquay airports."
www.EasternAirways.com www.sutton-harbour.co.uk