The 32-year-old, who made just four appearances for the Rams - three as a starter, was signed in January as a free agent after impressing manager Paul Jewell during a trial.
However, Jewell has since revealed things "didn't quite work out" for Robert at Pride Park, adding to the club's official website: "We wish him well in the future."
The nine-cap French international has now been unveiled as a Toronto player in the MLS, where the regular season began late last month.
John Carver: "I've spent a lot of time with him, and I know a lot about his game.
"He'll be a big asset to the team, he's got pace, his ability on free kicks is top class and he's a great finisher."
2000/05 L.Robert 155/26 32
French player who was a last minute signing from Paris St Germain after Zenden let down Bobby Robson and joined Chelsea rather than Newcastle. Tricky left-winger who started brilliantly, but suffered after a game against Liverpool when Jamie Carragher kicked him from one end of the field to the other. Went through a lull, but pulled himself out of it. Cost £9.5m. Had trouble with Robson because he insisted telling the world his thoughts on his website. Souness arrived and said he was a waste of talent because he only looked good going forward. Joined Portsmouth in 2005 but left with a parting shot for Souness.