Martijn Keizer (born 25 March 1988) is a Dutch professional road racing cyclist, who last competed for UCI WorldTeam LottoNL–Jumbo.
Keizer joined Veranclassic–Doltcini for the 2014 season, after his previous team – Vacansoleil–DCM – folded at the end of the 2013 season.
However, before he had competed in a race with the team, Keizer left the team after he was offered a contract to return to the top level – the UCI World Tour – with Belkin Pro Cycling.