The 33-year old Clark had three goals and 17 assists in 64 games with the Colorado Avalanche last season. He also appeared in one of the Avs' playoff games.
"In Brett Clark, we are adding an experienced, intelligent defenseman who plays the game efficiently," Yzerman said in a statement. "He'll not only help steady and stabilize our defense, we expect him to help mentor our younger defensemen as they grow and develop. We are pleased he elected to join the Lightning today."
Over 517 games, split between Colorado, Montreal and Atlanta, Clark has 34 goals and 105 assists and is a minus-27.
If the numbers are correct, the Wapella, Saskatchewan native will take a slight pay cut from the $3.5 million he earned last season.