The 19-year-old, who impressed for Belgium at the World Cup in Brazil, agreed to join the Reds from Lille earlier this summer, but has been loaned back to the French outfit for the 2014-15 campaign.
"He is a very exciting player and a huge prospect, and he will have one more year with Lille," Mignolet told the club's official website. "I'm sure that after that he'll play very well for Liverpool. He's got a huge future ahead of him.
"When we arrived with the Belgium squad, nobody had really heard about him to be honest. He played at Lille but had never been called up for the full squad, just the U21s.
"Because Christian Benteke was unfortunately injured, we needed a striker - he came in and from the first day in training he showed his ability. In the games, he showed what he was all about."
Liverpool opened their league campaign with a 2-1 victory over Southampton at Anfield last Sunday.