The 32-year-old forward was in Ottawa training camp on a professional tryout contract after scoring nine points (three goals, six assists) in 30 games for the Edmonton Oilers last season.
Ennis has been held without a point in three preseason games with the Senators, for whom he scored 33 points (14 goals, 19 assists) in 2019-20.
"Tyler has had a strong training camp," Senators general manager Pierre Dorion said. "He's a highly skilled veteran whose leadership qualities should prove as valuable as they were here two seasons ago. He's capable of generating offence both at 5-on-5 and on the power play, and with an ability to play both wing positions, he'll be a good addition for us at forward."
A first-round pick (No. 26) by the Buffalo Sabres in the 2008 NHL Draft, Ennis has scored 322 points (136 goals, 186 assists) in 643 regular-season games with the Sabres, Minnesota Wild, Toronto Maple Leafs, Senators and Oilers. He has 12 points (four goals, eight assists) in 24 Stanley Cup Playoff games.
