The German winger made just six Premier League appearances for the Blues despite being contracted to the Blues from July 2012 until August this year.
After his first season at Stamford Bridge he was sent out on loan and had spells with Sevilla, Fiorentina, Anderlecht and Trabzonspor.
He was finally sold to Olympiakos for £3m in the summer.
And despite failing to make an impact for Chelsea, Marin has no regrets about the move.
“I’m still happy that I was a part of Chelsea and I’m still a Chelsea fan”
Marko Marin opens up on his time at Stamford Bridge
“I’m still happy that I was a part of Chelsea and I’m still a Chelsea fan,” he told Goal.
“I went there with the hope to play and started very well in pre-season then I got a big injury and it was difficult to get back in the team.
“Maybe I didn’t get enough chances to play in a couple of games to show my qualities but Chelsea always has very good players and it’s difficult to play.”
Marin also praised the club’s loan system, despite the sheer quantity of players the Blues have at other clubs.
He added: “[We Skyped] once a month. After every game they sent me analysis of the game.
“Chelsea did a great job with every loan player in this group – with Paulo Ferreira and Eddie Newton who keep in touch with the players.”