The move is not surprising given the injury to starting goaltender Craig Anderson on Thursday night.
Anderson landed awkwardly after being knocked over by New York Rangers forward Chris Kreider. Anderson required the aide of a trainer and a teammate in order to get off the playing surface. It appeared as though he could not put pressure on his leg.
Following the game, the Senators listed Anderson as "day-to-day" with an ankle sprain.
Lehner has been performing at a high level in the AHL and has compiled an 18-10-2 record with a .938 save percentage, as well as a 2.12 goals against average. The 21-year-old goaltender has made 13 career NHL appearances and has a 4-6-0 record with a .910 save percentage and 2.81 goals against average.