The Reds return to the elite competition for the first time in five years when they take on Bulgarian side Ludogorets Razgrad on Tuesday.
The match comes three days after Liverpool suffered a 1-0 defeat on home turf against Aston Villa at the weekend.
"I'm looking forward to seeing what it's going to be like," Mignolet told the Liverpool Echo. "I've heard that the atmosphere at Anfield on European nights is always something special.
"But our focus must be on doing our jobs and making sure we get off to a winning start. It's really important that we start the group with three points."
Brendan Rodgers's side will also face Basel and reigning champions Real Madrid in Group B.