Lewes Travel was established 58 years ago by owner Richard Powell, who will now retire.
Baldwins Travel director Nick Marks said: “Richard wasn’t necessarily looking to sell, but when I heard he wanted to retire I decided to approach him.
“It’s a very good fit for us in terms of ethos and customer service.”
Baldwins already has stores in Tunbridge Wells, Tonbridge, Sevenoaks, Maidstone, Uckfield, Tenterden and Cranbrook, with its closest branch around 15 miles away from Lewes.
Marks said that as an affluent market town, Lewes has a lot of potential: “There is a Thomas Cook in the town but we believe we’ll be the only independent.”