He signed for Bristol City on 30 July 2007. After a successful first season with Bristol City, Elliott established himself as a popular member of the squad and impressed his fellow professionals as well, being named in the P.F.A Team of the Year alongside team-mate Bradley Orr. He also won Bristol City's 'Young Player of The Year' award in his first year at the club. In The summer of 2009, the 24-year-old was a target for several Premier League clubs, including Fulham, Wolves, Blackburn, Portsmouth and West Brom – who had a bid rejected in January. He subsequently signed a new 3 year deal which would keep him at Bristol City until the end of the 2011–12 Football League Championship. On 21 February 2012, Elliott snapped his Achilles during a training session ruling him out for the rest of the season. Manager Derek McInnes said in an interview We're absolutely devastated for the lad. "It's a massive blow and Marvin was desperate to play his part in keeping us in the Championship. "It happened in training, right near the end of the session today. He was running for the ball with no one near him, there was no contact with anyone. He just pulled up in a lot of pain and you knew it was serious.
"He's had it checked out and the only positive is that he won't require surgery. He'll be back in four months for pre-season and we'll be doing all we can to be a Championship club for when he returns."