Ennis signed on Friday and returns to the Atlantic Division, where he spent his first eight seasons playing for Buffalo.
Though undersized at 5-foot-9 and 160 pounds, Ennis is a speedy, playmaking forward who topped 20 goals in three of his nine NHL seasons. He joins his third team in two years after the Sabres traded him to Minnesota last summer.
A series of injuries led to Ennis scoring just eight goals and 24 points in 84 games over his final two years in Buffalo.
He had eight goals and 22 points in 73 games last season, and was due to make a $3.65 million salary next year before the Wild bought out the contract.
The Maple Leafs are in need of low-priced, experienced forwards after signing former New York Islanders captain John Tavares to a seven-year, $77 million contract on Sunday. They also lost forwards James van Riemsdyk and Tyler Bozak in free agency.