Per Major League Soccer and club policy, terms of the trade will not be disclosed.
"We want to thank Terry for the contribution he made to our club over the past year," said Whitecaps FC president Bob Lenarduzzi. "Being from Vancouver, Terry took pride in helping us make our move up to Major League Soccer, so today's trade was a difficult decision to make. We wish him all the best for the future at Toronto FC."
Dunfield, 29, scored one goal and added three assists in 12 MLS regular season matches for Whitecaps FC. Dunfield also scored one goal in four starts in this year's Nutrilite Canadian Championship.
Dunfield originally joined Whitecaps FC last August during the 2010 United States Soccer Federation Division-2 Pro League season.