Coutinho has been in sublime form in 2016-17 and has netted 12 goals in 30 Premier League appearances.
The attacking midfielder's performances have been vital to Liverpool's Champions League ambitions, with Jurgen Klopp's men to secure a top-four finish with a win over Middlesbrough on Sunday, and Mignolet has nothing but praise for his team-mate.
"They cannot really put one marker on to him. Philippe can distribute the ball in a brilliant way," Mignolet told the Liverpool Echo.
"In the Premier League you need creative players to open games up. You look at Chelsea, they have Eden Hazard. Manchester City have Raheem Sterling, David Silva or Kevin De Bruyne.
"He is a good boy who works hard. He is very important to us.
"It was a big positive that he signed that new contract. We all hope he stays at Liverpool for many years to come."