The 25-year-old Belgian has only won two races in his career but is considered a future cobbled Classics winner. He won Omloop Het Nieuwsblad in 2012 and was second in last year's Paris-Roubaix despite an injury-hit spring.
Vanmarcke was third at Kuurne-Brussels-Kuurne this year and fourth at Omloop Het Nieuwsblad. He will lead the Belkin team in the Classics this spring, alongside Lars Boom. No details of Vanmarcke's contract were revealed.
“Sep is a diamond in the rough. Especially when it comes to the Flemish Classic races," Belkin team manager Richard Plugge said in a press release confirming the news.
"Sep is a very strong guy, who has a lot of potential. It is only logical that we wanted to extend his contract, we want to keep the backbone of our team as strong as possible.”
"He is a team player and knows that you can achieve more when you do things together. During this time of the year, his teammates work for him, but in other race he puts in a lot of efforts for others, like for example in last year’s Tour de France.”
Vanmarcke tweeted that he was happy to have signed a new contract that will run to the end of 2016.
“Team Belkin is my best option when I look at my future,” he said in the team statement.
“I feel at home here. There is a lot of mutual trust and the team does everything in its power to assist me in the Classics, which is very important to me. The whole team is very motivated. The sports directors have strong ties with the Cruyff Institute and it is good to see that they, just like the riders, work hard to improve.”
Belkin sports director Nico Verhoeven has high hopes for Vanmarcke in the Classics.
“We hope to win the Tour of Flanders or Paris-Roubaix with him," he said.
"Last year, despite a knee injury, Sep was second in Roubaix. That proves that he’s a big rider. He’s one of the best classic riders in the world. We both feel that we are on the right track together. As a team we are very pleased that we have been able to tie Sep down for two more years.”