The club announced early Sunday morning that it has signed the guard-forward after the New York Knicks chose to not match Toronto's offer sheet for the restricted free agent.
The Raptors signed Fields to an offer sheet Wednesday. Under the terms of the NBA's collective bargaining agreement, the Knicks had three days to match the Raptors' offer beginning Thursday.
The deal is believed to be worth about US$20 million over three years.
The six-foot-seven, 215-pound Fields has averaged 9.3 points and 5.4 rebounds in 148 games over two seasons.
Fields was a selected to the NBA's all-rookie team in 2010-11 and was twice named Eastern Conference rookie of the month.