The 36-year-old goalie was 20-11-2 with a 2.58 goals-against average, .912 save percentage and two shutouts in 33 regular-season games with the Carolina Hurricanes last season after he was claimed off waivers from the Toronto Maple Leafs on Oct. 2, 2018.
McElhinney was 3-2 with a 2.01 GAA and .930 save percentage in five Stanley Cup Playoff games last season.
RELATED: [NHL Free Agent tracker]
He is likely to be the backup to Andrei Vasilevskiy with Tampa Bay.
"He's someone we've always liked," Lightning general manager Julien BriseBois said. "He knows the role and is a strong backup in that [veteran role]."
Selected by the Calgary Flames in the sixth round (No. 176) of the 2002 NHL Draft, McElhinney is 82-82-15 with a 2.81 GAA, .909 save percentage and 10 shutouts in 219 regular-season games (168 starts) with the Hurricanes, Maple Leafs, Columbus Blue Jackets, Arizona Coyotes, Ottawa Senators, Anaheim Ducks and Flames.
He is 3-3 with a 2.40 GAA and .913 save percentage in seven playoff games.