The former River Plate forward spent almost three seasons at Stade Louis II but was brought in by fellow Argentine and Marseille coach Marcelo Bielsa to help the south-coast club's bid for the French title.
With just two points separating the top three of Lyon, Marseille and Paris Saint-Germain, there is everything to play for with Ocampos bidding to add to the Ligue 2 crown he won with Monaco.
"This is a big club with many great players and a good coach, that's why I came here, to play for the title," he told Marseille's official website.
"Marcelo Bielsa is a great coach and all players who have worked with him have progressed at his side. This is a team that plays good football, which has very good players.
"I feel ready physically. My last game was more than two weeks ago but I am available to the coach."
