On 1 February 2016, Fletcher joined Ligue 1 side Marseille on loan until the end of the season. He made his debut for the club six days later, coming on as a second-half substitute for Michy Batshuayi in a 2–1 loss to rivals Paris Saint-Germain in "Le Classique" at the Stade Vélodrome. On 11 February, Fletcher made his full debut in a 2–0 Coupe de France win at fourth-tier amateur side Trélissac, setting up Romain Alessandrini for the first goal before netting himself in the 87th minute.