The Belgian, who was the subject of a £10 million switch from Sunderland in June, is expected to compete with Pepe Reina for the number one spot at Anfield next season.
The 24-year-old shot-stopper is confident he will improve at the Merseyside club, and hopes to help Brendan Rodgers' side push on next season and challenge for a top-four finish.
"For me it's a big step forward and I'm very pleased to be training with the team for two weeks now. I spoke to the manager and he told me that it's going to be a big step forward," Mignolet told the club's official website.
|13/8||Liverpool are 13/8 with Coral to finish in the top four
"When I came in for the first couple of training sessions, I saw that everybody is very hungry and ambitious to get going, everybody wants to take a step forward and push on into the top four.
"There's big ambition around the club. I also noticed that from the conversations I had with the goalkeeping coach and the gaffer. I saw that they are very ambitious, want to get forward, winning trophies and getting into the top four."
Like Mignolet, Kolo Toure is among the four signings made by Rodgers since the opening of the transfer window, having arrived on a free transfer from Manchester City on July 1.
And, speaking at the pair's official unveiling at the club's Melwood training ground, the Ivorian expressed his delight over sealing a move to Anfield.
"For me, it's an honour to play for Liverpool - this club is unbelievable," said Toure.
"I've just been here for two weeks and I've seen a lot of fantastic things. I'm proud and I will give my best to this football club.
"When I had to decide, when I had the phone call from Liverpool, you can't joke with that. It's one of the biggest clubs in the Premier League. I was like, 'wow'."