The 27-year-old played three seasons in Toronto after a four-year run with KHL club Omsk Avangard. Putting up 23 points in his rookie campaign with the blue and white, and 17 in the next, MIkheyev emerged as a key depth piece for the Maple Leafs in 2021-22, posting 21 goals and 32 points through 53 games.
He added two goals and four points through seven games against the Tampa Bay Lightning in the post-season, Mikheyev's speed and quick hands proving a valuable asset among Toronto's bottom six, along with his penalty-kill skill and overall defensive ability.
Earlier Wednesday, Mikheyev took to Instagram to thank Toronto for his time with the club.
"I would like to say thank you to the Toronto Maple Leafs management, coaches, teammates and of course our fans for the last three years of total support, your sincere emotions and faith in me," the winger wrote. "It was an unforgettable time and a great experience!"
After earning $1.645 million per year on the two-year pact he just completed, Mikheyev will now earn $4.75 million per season for the next four years as he begins a new journey in Vancouver.
"Ilya will provide a lot of value in our middle six," GM Patrik Allvin said Wednesday of his club's new marquee signing. "His versatility and ability to do so many different things will be a huge boost to our group.
"Solid at both ends of the ice, Ilya's speed is a real difference maker. Not only does he kill penalties, but he also can create offensively as well."