Walker has been the subject of widespread criticism from Citizens supporters at a time when Pep Guardiola's side have won just one of their last 10 matches across all competitions.
The 34-year-old started as captain and played the full 90 minutes of Man City's 2-0 defeat to Juventus in Turin, a result that leaves the 2023 Champions League winners at risk of failing to qualify for the knockout rounds.
Walker has since taken to social media to confirm that he was the subject of "vile" racist abuse on Instagram after the match.
The England international posted an image of the message received from an unknown account, and said: "No one should ever be subject to the sort of vile, racist and threatening abuse I have received online since last night's match.
"@Instagram and the authorities need to stop this happening for the sake of all who are suffering this abuse. It is never acceptable."
Walker added: "To our fans, we will continue to work as a team to do better, to improve and to turn a corner together."
Shortly after Walker posted his message online, Man City issued their own statement on their official website.
The statement read: "Manchester City strongly condemns the racist abuse that Kyle Walker was subject to online following last night's fixture.
"We refuse to tolerate discrimination of any kind, regardless of whether that be in stadiums or online.
"We will be offering Kyle our full support following the disgusting treatment he has received."
Unfortunately, this is not the first time that Walker has been the subject of racist abuse, as the right-back was on the receiving end of sickening abuse in April 2021 after Man City's 1-0 EFL Cup final win over his former club Tottenham Hotspur.
Walker joined Man City from Spurs in 2017 and has since made a total of 315 appearances for Guardiola's side in all competitions, including 14 outings this season.
The experienced defender has played a significant role in Man City's recent success, winning a total of 17 trophies including six Premier League titles, two FA Cups, four EFL Cups and one Champions League.
Walker is expected to be involved in Man City's next Premier League game at home against rivals Manchester United at the Etihad Stadium on Sunday.
Written by
Oliver Thomas