The deal doesn't include any player or team options, league sources told The Athletic's Shams Charania.
Based on a $116-million salary cap for the 2020-21 NBA season, here's how Siakam's contract breaks down:
(Amounts courtesy of ESPN's Bobby Marks)
Siakam follows Ben Simmons and Jamal Murray as one of only three 2016 NBA Draft class members to receive a max contract extension.
He's coming off a breakthrough 2018-19 campaign, posting career highs in points (16.9), rebounds (6.9), and 3-point percentage (36.9%) en route to winning the NBA's Most Improved Player Award.
Siakam's emergence as a secondary offensive option helped the Raptors earn their first NBA championship this past season. He's now expected to be the go-to scorer following the offseason departure of Kawhi Leonard.
The Cameroonian also demonstrated great defensive versatility, guarding multiple positions with his athleticism and length. Siakam led all players last season with 375 contested 3-point shots, according to NBA.com.