After an early career in karting, Marsoin made his racing debut in 2005 in the Formula Renault Campus France series, finishing the year in eighth position.

The following year he moved up to the French Formula Renault championship with the Epsilon Sport team, taking a single podium finish and fastest lap on his way to twelfth in the standings.

Driving for SG Formula in the French series, he took six podiums, including two race wins, to finish third in the championship, behind team-mate and champion Jules Bianchi.

In late 2007, Marsoin took part in Formula Renault 3.5 Series testing at the Circuit Paul Ricard and Circuit de Valencia with the Belgian KTR team, and in February 2008 he was signed by Spanish team Epsilon Euskadi to partner fellow rookie Mario Romancini.

[3] Marsoin replaced Jon Lancaster for the opening round of the 2009 Formula Three Euroseries season at Hockenheim.