The 30-year-old has put pen to paper on a deal that will see him play his football at the Memorial Stadium this season.
Having decided to leave Lincoln City at the end of his short-term deal, Marquis held talks with Barton over a possible move to the club.
Marquis has mainly played in the third tier throughout his 13-year playing career and bolsters the front line at the Mem, joining Aaron Collins, Harvey Saunders and Ryan Loft as another attacking option.
“We are excited to be able to announce that John Marquis has signed for Bristol Rovers,” Barton said.
“John is a player I’ve admired for some time. He is a real coup for us, a proven goalscorer at League One level and a great addition.
“After speaking to him over the last few weeks it was clear that, like me, he believes he can continue to improve. Our group will continue to push to get better every day and John will fit in superbly.
“John is keen to get going and will fly out tonight to join up with us in Portugal in what has already been a really solid few days of training.”
Before joining up with the squad in Portugal, Marquis had already begun his own strict regime to get him into shape for the upcoming season. He sought the help of a personal trainer in Dubai to help prepare him for the upcoming season.
The experienced forward will now link up with his teammates for the week also abroad as he takes in the first few days as a new player of Bristol Rovers, where he will hope to impress Barton enough for a starting spot.
Across the non-league and professional game, he has scored a total of 144 goals in 459 games and has a winning pedigree. In the 2018/19 season he was included in the Team of the Year after scoring 21 goals in 44 games for a Doncaster Rovers team that reached the play-offs.
He was also named their player of the year after netting 26 goals in 45 games back in League Two and in five of his last six seasons he has reached double figures.
In his career, Marquis has scored four times against Rovers but now will be tasked with scoring the goals to make the team competitive this season.
Rovers had been in the market for a striker and had reportedly held talks with James Norwood but following the arrival of Marquis, they may opt to go in a different direction.
They did let both Brett Pitman and Leon Clarke leave however and a fourth option in attack would be welcomed as enough squad depth but there is still a considerable amount of time left in the window.
A further four to five signings are expected to arrive at the club after comments from Joey Barton last week.