Before the start of the 2017–18 season, Firmino switched his shirt number to 9, with new signing Mohamed Salah taking his number 11.
Firmino scored his first goal of the new season on 12 August, scoring a penalty in a 3–3 draw with Watford.
On 17 December, he scored in a 4–0 away win over AFC Bournemouth; a result which saw Liverpool become the first team in Premier League history to win four consecutive away games by a margin of at least three goals.

On 5 January 2018, during a FA Cup match against rivals Everton, Firmino was the subject of controversy following a clash with Everton defender Mason Holgate.
Holgate pushed Firmino into the advertising boards, which was followed by the pair exchanging words, with Firmino seemingly insulting the player.
Following the match, Holgate accused Firmino of racially abusing him, which he denied.
A day later, the Football Association opened an investigation on the matter.
Nearly two months later, after they had took statements from 12 different players, several referees and consulted two Portuguese lip-readers, the Football Association cleared Firmino of any offence as a result of "insufficient evidence".

On 14 January, Firmino scored in a 4–3 home win over Manchester City; which saw Liverpool end City's unbeaten league run.
On 10 April, he scored in a 2–1 win over Manchester City in the second leg of the quarter-finals of the Champions League; which saw Liverpool advance to the semi-finals with a 5–1 aggregate win.
Firmino started and played the whole 90 minutes in the 2018 UEFA Champions League Final, with Liverpool losing 3–1.

During the season, Firmino, Mohamed Salah, Philippe Coutinho and Sadio Mané made up a prolific attacking quarter, dubbed the "Fab Four", in reference to the rock band The Beatles, also from the same city as the club.
Following the mid-season exit of Coutinho, the three remaining players were dubbed as the "Fab Three", with the trio having a total of 91 goals between them at the end of the season.
Firmino was Liverpool's joint top goalscorer in the UEFA Champions League, together with Salah, with 11 goals.
Firmino was also included in the 2017–18 UEFA Champions League Squad of the Season.
The 2017–18 season was Firmino's most prolific in his Liverpool career; as he scored 27 goals in all competitions.
Before the start of the 2017–18 season, Firmino switched his shirt number to 9, with new signing Mohamed Salah taking his number 11. Firmino scored his first goal of the new season on 12 August, scoring a penalty in a 3–3 draw with Watford. On 17 December, he scored in a 4–0 away win over AFC Bournemouth; a result which saw Liverpool become the first team in Premier League history to win four consecutive away games by a margin of at least three goals.
On 5 January 2018, during a FA Cup match against rivals Everton, Firmino was the subject of controversy following a clash with Everton defender Mason Holgate. Holgate pushed Firmino into the advertising boards, which was followed by the pair exchanging words, with Firmino seemingly insulting the player. Following the match, Holgate accused Firmino of racially abusing him, which he denied. A day later, the Football Association opened an investigation on the matter. Nearly two months later, after they had took statements from 12 different players, several referees and consulted two Portuguese lip-readers, the Football Association cleared Firmino of any offence as a result of "insufficient evidence".
On 14 January, Firmino scored in a 4–3 home win over Manchester City; which saw Liverpool end City's unbeaten league run. On 10 April, he scored in a 2–1 win over Manchester City in the second leg of the quarter-finals of the Champions League; which saw Liverpool advance to the semi-finals with a 5–1 aggregate win. Firmino started and played the whole 90 minutes in the 2018 UEFA Champions League Final, with Liverpool losing 3–1.
During the season, Firmino, Mohamed Salah, Philippe Coutinho and Sadio Mané made up a prolific attacking quarter, dubbed the "Fab Four", in reference to the rock band The Beatles, also from the same city as the club. Following the mid-season exit of Coutinho, the three remaining players were dubbed as the "Fab Three", with the trio having a total of 91 goals between them at the end of the season. Firmino was Liverpool's joint top goalscorer in the UEFA Champions League, together with Salah, with 11 goals. Firmino was also included in the 2017–18 UEFA Champions League Squad of the Season. The 2017–18 season was Firmino's most prolific in his Liverpool career; as he scored 27 goals in all competitions.
Roberto Firmino