Alisson has put pen-to-paper on a six-year contract that ties him to Liverpool until the summer of 2027.
The 28-year-old joined Liverpool from AS Roma in the summer of 2018 and has made 130 appearances across all competitions for Jurgen Klopp's men.
Alisson has won the Premier League, UEFA Champions League and FIFA Club World Cup during his time on the red side of Merseyside.
Alisson joins compatriot Fabinho and Trent Alexander-Arnold in signing new contracts at Anfield.
Speaking to Liverpoolfc.com, Alisson said: "I think I didn't waste too much time to think about that. It's something we just built in those last three years, the confidence, the trust that I have in the club and the club has in myself.
"Me and my family, we are really happy here. My kids are settled in England, in a different country, but they are growing up in that way.
"So we are really happy. I'm really glad that I can keep going on with my work here, doing a good job here. So, I'm really happy to make this decision - that is not hard for me."
Alisson won Liverpool’s goal of the season last term, with his last-minute headed winner against West Bromwich Albion proving crucial in the Reds securing a Champions League spot in a troubled campaign.
Liverpool will begin their 2021/2022 campaign away at Norwich City on August 14.