The 25-year-old began his career with French side Auxerre and made one senior appearance for them in Ligue 1.
France-born Missilou has also had spells with Brest, FC Montceau, Entente SSG and most recently Le Puy Foot.
He played for a clutch of lower-tier French clubs before making the move to England and signed for Oldham in the summer of 2018.
He spent two seasons at Boundary Park, making 77 first-team appearances.
Missilou started for Oldham in their past three meetings against the Cobblers.