Roberts' contract is set to expire and the Championship club have taken the decision not to offer the 35-year-old a new deal.
Saturday's game against the Lions will be his final appearance for the Rams.
Manager Nigel Clough told the club's official website: "Gareth has been incredible for the three years he has been here and the supporters have acknowledged that.
"Physically he is in a great shape, even in pre-season when he came back in July last year he put a lot of the younger lads to shame. He has been a wonderful servant for three years and we will be doing all we can to help secure his future elsewhere.
"He has been helping out with the coaching at the academy as well, so there is a possibility that he might still be around the place."
Roberts joined Derby on a free transfer in the summer of 2010 following his release by Doncaster. His only goal for the Rams came in a 2-1 win against his former team in March 2012, and his contract was extended by a further year shortly afterwards.
During the current campaign, Roberts has made 31 appearances for Derby
and made his 600th senior club appearance against Peterborough at London Road in October.
Clough, meanwhile, admits he faces goalkeeping "issues" this summer.
Injury and suspension problems have meant that Frank Fielding and Adam Legzdins have both had runs in the team this season.
Fielding, first choice for the majority of last season, also began this campaign as number one before suffering a groin injury at Middlesbrough in October which opened the door for Legzdins to make 30 consecutive starts.
Legzdins was then replaced at the start of March, but a red card for Fielding in the home victory over Peterborough on April 20 gave him another chance.
Both keepers are about to enter the final year of their contracts and Clough admits he faces a tough decision about what to do.
"The goalkeeping department is an area we are looking at, certainly. We have got contract issues there," said Clough.
"They have both got a year left so that needs sorting one way or another, first of all.
"It is the same with any player who has a year left, they either sign another contract or they go. We cannot let them go into their final year.
"I don't know whether we are lucky or unlucky in the respect that we have two very good goalkeepers who are both number one's really."