Remy, 23, was diagnosed with a heart defect last week after joining on a five-year contract from Nice.
The striker, who has two international caps, underwent further tests on Monday and results showed he could safely play at the highest level.
"A panel of medical experts said the results were reassuring," Olympique Marseille doctor Christophe Baudot told reporters.
"You're not in the best conditions when you're told your career could be over," he said. "But now I feel relieved. It's taken a weight off my mind and I'm ready to play on Sunday."
Marseille president Jean-Claude Dassier said he would ask Nice why they did not inform them of Remy's problem before they sold him.
Last year, forward Steve Savidan's move from Caen to Monaco collapsed for the same reason and he too had to hang up his boots.
