[6][9] Having progressed through the youth set up, he featured regularly with the under-23 side, before making his senior debut on 17 February 2013, starting in a 1–1 away draw against Cruzeiro-RS in the Campeonato Gaúcho championship.

[14] During his four years with Internacional's senior side, Alisson made over 100 appearances across all competitions and won the Campeonato Gaúcho title in each season.

[15] He made his debut for the club on 17 August 2016, starting in a 1–1 UEFA Champions League draw with Porto, but spent the majority of the season as understudy to Wojciech Szczęsny.

[20][21] The club didn't concede a single goal at the Stadio Olimpico in the Champions League, until the match against Liverpool in the semi-finals on 2 May 2018, which they won 4–2 on the night, but lost 7–6 on aggregate.

[36] However, with Alisson in goal, Liverpool went on a run of 20 games unbeaten in the league from the start of the season which saw the Brazilian break Javier Mascherano's record for the longest-such streak.

[40] In the Champions League knockout stages, meanwhile, Alisson played a starring role as Liverpool advanced to their second consecutive final in the competition; in their second-leg semi-final at home to Barcelona, he made a number of impressive saves as Liverpool overturned a 3–0 first leg deficit to advance past their opponents with a 4–0 home win.

[41] In the final on 1 June 2019, Alisson kept a clean sheet for Liverpool as they defeated Tottenham Hotspur 2–0, making eight saves in the process, to win his first trophy with the club.

[45] On 9 August 2019, in the opening match of the 2019–20 Premier League season against newly promoted Norwich at Anfield, Alisson picked up a calf injury in the first half, and had to be replaced by new signing Adrián after 38 minutes.

[51] On 21 December, Alisson kept a clean sheet against Flamengo in the 2019 FIFA Club World Cup final with Liverpool winning the trophy for the first time.

[57] On 7 February 2021, Alisson made two errors in the space of three minutes, conceding possession to allow Manchester City's İlkay Gündoğan and Raheem Sterling to score, as Liverpool lost 4–1.

[60] On 4 August 2021, prior to the beginning of the 2021–22 Premier League season, Alisson signed a new contract extension to stay with Liverpool until the summer of 2027.

[65] Three days later, on 19 October, Alisson saved a penalty from Jarrod Bowen as Liverpool beat West Ham United 1–0 in the Premier League.

[72] He marked his return from injury by keeping a clean sheet in Liverpool’s 1-0 away win against Girona in the UEFA Champions League on 10 December 2024.

[73] After representing Brazil at under-17 and under-20 levels, Alisson was called up to the senior squad by manager Dunga for the first two matches of the 2018 FIFA World Cup qualification campaign against Chile and Venezuela.

[76] In the team's first match, a goalless draw against Ecuador, he fumbled a Miller Bolaños shot into his own goal that was waved off because the ball had gone out of play beforehand.

The only match in which Alisson failed to keep a clean sheet was the 3–1 final victory against Peru on 7 July, at the Maracanã Stadium, in which he was beaten by a Paolo Guerrero penalty.

[83] On 13 June 2021, he started in Brazil's opening match of the 2021 Copa América on home soil, keeping a clean sheet in a 3–0 win over Venezuela.

[87] He played 2 group stage games before being rested against Cameroon, then started both knockout matches, although he was subbed out in the 80th minute against South Korea.

Alisson has been praised for his ability to produce crucial saves and brilliance in one-on-one situations, as well as his positioning, distribution and consistency;[88][89][90] he is rated by some in the sport as the best goalkeeper in the world.

[91][92][93] Alisson cites former Barcelona goalkeeper Víctor Valdés as an inspiration, due to his ability to play out from the back, as well as Manuel Neuer, for his 'sweeper keeper' style.

His skills with the ball at his feet and composure in possession have even seen him take on opponents on occasion, when put under pressure, and allow his teams to play with a high defensive line.

[1][93][101] He possesses good reflexes and excellent shot-stopping abilities, as well as the capacity to produce spectacular and instinctive reaction saves when necessary, but he is predominantly known for his efficient style of goalkeeping, courtesy of his anticipation, consistency, composure, intelligence, positional sense, and goalkeeping technique, which enables him to read the game, cover the goal well, and stop shots without having to resort to histrionics.

Alisson is regarded by some sport pundits, due to his statistical performances, as the most proficient goalkeeper in the Premier League, and arguably even the best in the world, when left in an individual battle with an opponent.

[125][126] He has been nicknamed "The Holy Goalie" by teammate Virgil van Dijk due to his faith, and lifted the Champions League trophy wearing a T-shirt with "† = ❤" on it.