In August 2017, Liverpool rejected a £72 million bid from Barcelona for Coutinho, prompting the player to submit a transfer request over email.
Two more improved bids from Barcelona were rejected, leading Barça director Albert Soler to claim Liverpool wanted £183 million for Coutinho, which Liverpool denied.
Coutinho made his first appearance of the season for Liverpool on 13 September 2017, coming on as a substitute for Emre Can in the 75th minute of a 2–2 draw against Sevilla in the UEFA Champions League.
He scored his first Premier League goal of the season on 23 September 2017 in a 3–2 victory at Leicester City.

On 6 December, Coutinho captained Liverpool for the first time in the absence of Jordan Henderson and scored his first hat-trick for the club in a 7–0 win against Spartak Moscow in the final group stage match of the season's Champions League.
His second, a tap-in from Roberto Firmino's pass, was his 50th career goal for the Reds in all competitions.
Coutinho had previously also netted in Liverpool's 7–0 victory over Maribor which was the club's joint-largest ever away win in the competition, and largest away win by an English club.
Later that month, he opened the scoring in a 4–0 win over AFC Bournemouth, a result which saw Liverpool become the first team in Premier League history to win four consecutive league matches by at least a three-goal margin.
On 26 December, he captained Liverpool in his 200th appearance for the club, scoring once and providing an assist in a 5–0 league win over Swansea City to score his third goal in as many league matches.

Coutinho played what transpired to be his final match for Liverpool on 30 December 2017, featuring prominently in a 2–1 league win against Leicester City at Anfield.
On 31 December, sportswear company Nike—Coutinho and Barcelona's sponsor—advertised Coutinho's image on the back of a Barcelona shirt, despite Coutinho still being a Liverpool player at the time.
Coutinho was omitted from the Liverpool squad to face Burnley on New Year's Day with a minor thigh injury.
He left Liverpool having registered 12 goals and 9 assists in 20 appearances for the club in 2017–18.

Liverpool chairman Tom Werner said "I only have good things to say about Philippe, but I think he left Liverpool because he wanted to play for one of the two big Spanish clubs.
We tried to convince him that we had the club moving in the right direction and that he could experience great nights in the Champions League if he stayed in Liverpool".
 Coutinho "lost a lot of support for the manner in which he forced through a move to Barcelona".

Two years later, various football commentators noted that Coutinho's transfer to Barcelona, was instrumental in providing the funds necessary, for Liverpool to purchase the transfer rights of both Virgil Van Dijk (from Southampton F.C. for £75 million, then a world-record transfer fee for a defender, in the 2018 January transfer window) and Alisson (from A.S. Roma for £66.9 million, then a world-record transfer fee for a goalkeeper, in the 2018 summer transfer window).
Virgil Van Dijk and Alisson have both been identified as two of the most pivotal players in Liverpool's successes of winning the 2018-19 UEFA Champions League as well as the 2019-20 Premier League.
In August 2017, Liverpool rejected a £72 million bid from Barcelona for Coutinho, prompting the player to submit a transfer request over email. Two more improved bids from Barcelona were rejected, leading Barça director Albert Soler to claim Liverpool wanted £183 million for Coutinho, which Liverpool denied. Coutinho made his first appearance of the season for Liverpool on 13 September 2017, coming on as a substitute for Emre Can in the 75th minute of a 2–2 draw against Sevilla in the UEFA Champions League. He scored his first Premier League goal of the season on 23 September 2017 in a 3–2 victory at Leicester City.
On 6 December, Coutinho captained Liverpool for the first time in the absence of Jordan Henderson and scored his first hat-trick for the club in a 7–0 win against Spartak Moscow in the final group stage match of the season's Champions League. His second, a tap-in from Roberto Firmino's pass, was his 50th career goal for the Reds in all competitions. Coutinho had previously also netted in Liverpool's 7–0 victory over Maribor which was the club's joint-largest ever away win in the competition, and largest away win by an English club. Later that month, he opened the scoring in a 4–0 win over AFC Bournemouth, a result which saw Liverpool become the first team in Premier League history to win four consecutive league matches by at least a three-goal margin. On 26 December, he captained Liverpool in his 200th appearance for the club, scoring once and providing an assist in a 5–0 league win over Swansea City to score his third goal in as many league matches.
Coutinho played what transpired to be his final match for Liverpool on 30 December 2017, featuring prominently in a 2–1 league win against Leicester City at Anfield. On 31 December, sportswear company Nike—Coutinho and Barcelona's sponsor—advertised Coutinho's image on the back of a Barcelona shirt, despite Coutinho still being a Liverpool player at the time. Coutinho was omitted from the Liverpool squad to face Burnley on New Year's Day with a minor thigh injury. He left Liverpool having registered 12 goals and 9 assists in 20 appearances for the club in 2017–18.
Liverpool chairman Tom Werner said "I only have good things to say about Philippe, but I think he left Liverpool because he wanted to play for one of the two big Spanish clubs. We tried to convince him that we had the club moving in the right direction and that he could experience great nights in the Champions League if he stayed in Liverpool".  Coutinho "lost a lot of support for the manner in which he forced through a move to Barcelona". 
Two years later, various football commentators noted that Coutinho's transfer to Barcelona, was instrumental in providing the funds necessary, for Liverpool to purchase the transfer rights of both Virgil Van Dijk (from Southampton F.C. for £75 million, then a world-record transfer fee for a defender, in the 2018 January transfer window) and Alisson (from A.S. Roma for £66.9 million, then a world-record transfer fee for a goalkeeper, in the 2018 summer transfer window). Virgil Van Dijk and Alisson have both been identified as two of the most pivotal players in Liverpool's successes of winning the 2018-19 UEFA Champions League as well as the 2019-20 Premier League.
Philippe Coutinho