The signature of Upson is the first arrival of the summer of Rovers, as the twenty-eight-year-old joins the club as a free-agent, effective from the 1st July.
A product of the Ipswich Town academy, the midfielder navigated the ranks at Portman Road to sign his first professional at the age of seventeen.
Temporary spells on loan at both Barnet and Stevenage allowed Upson to gain a taste of first-team football, before switching to join Yeovil on a permanent basis in 2010.
His spell at Huish Park was a successful one, as he part of the Yeovil side that achieved promotion to the Championship in 2013-14, while cementing his place in the first-team.
A move to join Millwall followed, joining the south-London side for two full seasons in the Skybet Championship, with his stay at the New Den concluding with a season-long stint in the third tier of English football.
Upson was most recently part of the squad at MK Dons, where he featured heavily last season, tallying just shy of fifty appearances during the 2017/18 campaign.
In total, the midfielder is approaching three-hundred EFL appearances, with eighteen league goals to his name.
Speaking about the new addition to his squad, Manager Darrell Clarke added, “Ed is someone that I have admired for a number of years.”
“He’s a player that has a vast amount of experience at this level and at a higher level also.”
“Ed adds healthy competition to the central midfield positions and we are looking forward to having him on board.”
After finalising the paperwork at the Memorial Stadium this afternoon, the new recruit signalled his delight at getting the switch confirmed at the early stage of the off-season.
“I’m pleased to finally be here and to have the deal all sorted,” said Upson.
“I met the Manager early in the week and he’s a very ambitious person and I know the club is also very ambitious. I think the mixture of those two things could propel the club into the next division.”
The midfielder will link up with his new teammates for pre-season.