Liverpool have made Roma's Alisson the world's most expensive goalkeeper by signing him on a six-year deal.
The Reds have not revealed how much they have paid for the Brazil number one but Roma said the deal is worth up to £66.8 million, the BBC reports on Friday.
"In terms of my life and my career, it's a huge step for me being part of this club and this family," said the 25-year-old.
Alisson has been at Roma for two years, keeping 17 clean sheets in 37 Serie A appearances for Roma last season. He helped the club to reach the Champions League semi-finals, where they were knocked out by Liverpool.
The Brazilian started all five games at the World Cup in Russia where they bowed out with a quarter-final defeat by Belgium, according to Reuters.
'One of the world's best goalkeepers'
Liverpool manager Jurgen Klopp said he has signed "a real personality".
"At one point in the last few weeks it came up, the opportunity to sign one of the world's best goalkeepers," he added. "The owners were quite excited, so we did it."
"He has nothing to do with the price, we have nothing to do with the price. It's the market, that's how it is and we will not think a lot about it."
"We got him here because of his existing strengths, which is in all goalkeeper departments the highest level."
The goalkeeping position has been problematic for Liverpool under Klopp, with Loris Karius and Simon Mignolet struggling to hold down their first-team spots last season.
Karius endured a dismal night in last season’s Champions League final, making two blunders that led to goals in a 3-1 defeat to Real Madrid.
Alisson is Liverpool's fourth major signing since they finished the 2017-18 season fourth in the Premier League and were beaten by Real.
Brazil midfielder Fabinho, 24, has joined from Monaco in a deal which could be worth more than £40 million, while Guinea midfielder Naby Keita, 23, has moved to the Merseyside club from German side RB Leipzig in a £48 million deal.
Liverpool have also signed Switzerland forward Xherdan Shaqiri, 26, from Stoke City after triggering his £13 million release clause.
In addition, 26-year-old forward Salah - who has scored 44 goals in 52 appearances for the club - signed a new five-year contract this summer.