Samuel, a Trinidad & Tobago international, joins from Scottish Premier League side Dundee United on a free transfer after playing out his contract with the club.
The 25-year-old scored 14 goals in three seasons at Tannadice and Toronto coach Mo Johnston said: "We're excited to have him on board.
"I tried signing him two years ago when I was in New York.
"He's strong, he's fast, he can play left side, he can play right hand side and he can play through the middle.
"He's a great addition to our team, having (Danny) Dichio and (Jeff) Cunningham already."