Giovinco - who according to Italian press reports is set to earn €8.5 million a season - will form an attacking partnership with American international Jozy Altidore who was part of the swap deal for former England striker Jermain Defoe when he signed for English Premier League strugglers Sunderland last week.
"I am excited to sign for Toronto FC today and look forward to joining the club this summer," Giovinco told FC Toronto's site.
"I have heard so many great things about them over the years and I know that it will be a city that I feel right at home in."
Known as the 'Atomic Ant' (5ft 4in - 1m62) for his short stature coupled with a relentless work-rate the 27-year-old - capped 21 times - has lost his starting place at Juventus and has failed to score in seven appearances this season.
He was, however, an integral part of the Serie A championship winning sides in both 2013 and 2014.
Giovinco, who was at Juventus for seven years, was also in the Euro 2012 Italy squad that reached the final.
Toronto FC General Manager Tim Bezbatchenko was delighted with the acquisition.
"'Seba' is in the prime of his career and he has chosen to join Toronto FC and MLS at a time when many of the top clubs in the world were pursuing him," said Bezbatchenko.
"We are very pleased to bring a fantastic player to Toronto FC for our club and for our fans, especially those in the Italian community."