The Buffalo-born defenceman has signed a one-year, $875,000 deal with the Philadelphia Flyers, the NHL team announced Tuesday.
The Sabres traded Gilbert to the Ottawa Senators in the Josh Norris-Dylan Cozens deal last season.
Gilbert, 28, had six assists in 29 combined NHL games last season.
Gilbert has three goals and 17 assists in 111 career NHL games with the Chicago Blackhawks, Colorado Avalanche, Calgary Flames, Sabres and Senators.