The 23-year-old joined Nice on a six-month loan deal earlier in the January transfer window.
Digard struggled with injuries during his time at Boro since joining the club from Paris St Germain in June 2008.
“It had become difficult for me,” Digard told the Evening Gazette.
“The first year went well on a personal level and I was a regular until my injury in February.
“Unfortunately we fell into the second division, then the manager changed.
“With the reduction of its budget, the club had to make choices and try to part with some players.
“For me, it was necessary to leave to have the chance to play, for Boro that allowed them to save money, therefore I think that everybody got something out of it.
“I have learnt a lot, I played against the great teams and the best players in the world therefore it was an excellent experience.”
“I am here (Nice) to work hard for six months and hope to convince everybody in that period to keep me after that,” added Digard.
“I felt a real desire to come here because of the coach, our discussions went very well.
“I have seen a lot of matches on the TV, I think that Nice have a good team and that they deserve better than their current position.
“I know the style of the team and think I am able to bring more to it.”
