After a difficult start to the 2014-15 season that saw him dropped in December, Mignolet has re-established himself as Liverpool's number one keeper.
The Belgium international's return to the starting line-up has coincided with Liverpool's rise in the Premier League, with the 26-year-old keeping seven clean sheets as Brendan Rodgers' sit two points outside the top four.
And Clemence - regarded as Liverpool's greatest keeper after helping the club to five league titles and three European Cups between 1967-81 - believes Mignolet is reaping the rewards for his hard work.
"Simon deserves great credit for how he has turned things around," Clemence told the Liverpool Echo. "He's making vital saves and helping his team win matches.
"It just shows what a difference confidence makes. He had a tough time earlier in the season.
"After being left out he had the bonus of coming back into the team earlier than he would have expected after Brad Jones got injured. Since returning to the team he has got better and better.
"He hasn't surprised me because I knew he had it in him. He had an exceptional season for Sunderland before Liverpool bought him.
"Earlier this season he endured a spell where things weren't going right for him but he went away and worked on a few things.
"There are still a few areas I'm sure he'd like to improve on further but he's having an excellent time of it and long may it continue."
