The Italy international, who left the Bianconeri as a free agent when his contract expired last month, has secured a four-year deal with the MLS franchise.
Bernardeschi is the third Italian to join Toronto during this window, with Lorenzo Insigne and Domenico Criscito also arriving in Ontario.
The three-time Serie A title winner brings plenty of experience to the Reds' ranks, having also racked up 182 appearances for Juventus across all competitions, scoring 12 goals while providing 20 assists.
The 28-year-old winger has also earned 39 senior international caps and was part of Italy's UEFA Euro 2020-winning squad, scoring his spot-kick as the Azzurri beat England on penalties in the final.
"Having met with Federico a couple of weeks ago, we think he's a great fit for what we're trying to build here at TFC, and look forward to getting him on the field," Toronto head coach and sporting director Bob Bradley said.
Club president Bill Manning added: "We are thrilled to add Federico to our team. As a player and a person, we believe he's exactly what we need right now, both on the field and in the locker room.
"Federico has proven himself to be a champion and a leader at Juventus and for the Italian national team, and brings a pedigree to Toronto that's second to none."
Toronto is 13th in the Eastern Conference and aiming to end a four-game winless run when it travels to Montreal on Monday (AEST).