The Scotland No.8 took the player-of-the-match award and earned praise from his head coach and teammates in his first competitive game for seven months.
Dempsey has been out of action since March, when he picked up a hamstring injury before Scotland's final Six Nations game against France.
He played in Glasgow's pre-season game against Northampton, but picked up a groin injury in the warm-up before the opening URC fixture against Sharks, leading to another three weeks out.
Speaking to Premier Sports, Dempsey said: "It didn't feel good to be honest, coming back from six or seven months out and playing against one of the best teams in the comp, let alone the style they play. It was tough but it is easier when you have got these boys next to you; it makes it easier.
"When you get to my age - I'm 31 now - you kind of hope you learn how to find form quickly. It is just more getting the lungs used to it and the legs going again. When you play a team of that quality, it fast-tracks you in a way. It was good."
Glasgow skipper Kyle Steyn said Dempsey's return was "massive" for the Warriors.
"He is one of our best carriers and every time he comes back from injury, he normally puts in one of his best performances," Steyn said. "We're really buzzing to have him back. He is a big-game player for us and really stands up in those tough moments."
Sione Tuipulotu also had words of praise for Dempsey.
"Jeez bro, when he is fresh, he is a different animal," Tuipuloto told former Glasgow skipper, and Premier Sports presenter, Ryan Wilson.
"I was expecting him to be on it. I have known him a long time and I was expecting that type of performance. He is such a valuable asset for us. He just kept us going forward. You don’t need to call anything, you just give him the ball and let him go."
Head coach Franco Smith admitted he had contemplated replacing Dempsey but kept him on for the full 80 minutes, such was his impact on the game.
"He was fantastic," Smith said. "He really wanted to contribute and I think he would have been really unhappy with me if I had taken him off earlier! He managed the intensity of the game and applied himself really well. His performance is some accolade for all the hard work he has put in."