"While Plata is a player our fans enjoyed watching, he did not figure in our plans moving forward," Toronto president and GM Kevin Payne said in a statement. "It made sense for our club to move him for value as we can continue to build the team we want."
The five-foot-two 135-pound Plata scored 10 goals and added nine assists in 52 appearances in all competitions for Toronto.
"We are happy to add a fast, young forward with MLS experience," Real Salt Lake GM Garth Lagerwey said in a statement. "We believe that Joao can become an impactful member of our team as we continue to work to restock our forward group."
That restocking includes the return of striker Robbie Findley from two years in England and drafting New Mexico rookie forward Devon Sandoval.
Plata's days in Toronto seemed numbered after a messy loan deal with his former club in his native Ecuador was played out in public last summer.
Toronto FC insisted no loan deal had been complete while Plata tweeted he was leaving and was seen saying farewell to TFC teammates in the locker-room. Reports in Ecuador also said the loan deal was done.
At the time, Earl Cochrane, Toronto's director of team and player operations, said: "We're talking about a 19-, 20-year-old player who is being pulled in a couple of different directions and one of those directions is by a former club."
He was eventually sent to Ecuadorian side LDU Quito on a six-month loan deal in July.
Plata, 20, offered a burst of speed on the flank and often created problems for opposing defences. But he also seemed like a one-trick pony at times and upset his Toronto employers last summer by going public about leaving the club.
Plata was drafted in the third round (49th overall) in the 2011 SuperDraft after Toronto, via a late trade, decided to take a gamble on the pint-sized South American who was the leading scorer at the MLS Combine.
Plata has won one cap for Ecuador.
Toronto FC travels to Orlando on Friday to continue its pre-season ahead of the Walt Disney World Pro Soccer Classic tournament.
NOTES: Sporting Kansas City has loaned forward Kei Kamara to Norwich City of the English Premier League through May 6, pending Kamara getting his work permit. Kansas City will receive two-thirds of the loan fee to use as allocation money. If Norwich elects not to keep the player via full transfer by May 6, Kamara will rejoin Sporting Kansas City.