England defenders, Manchester City s English defender Kyle Walker. AFP
The alleged incident is said to have happened on Sunday, a day after Walker played in City's 2-0 Premier League win over Newcastle.
The Sun newspaper published security camera footage online on Wednesday that appears to show Walker twice pulling down his trousers in a bar in Wilmslow, 14 miles south of Manchester.
"On Wednesday 8 March, Cheshire police was made aware of a video circulating on social media in relation to an indecent exposure which allegedly occurred in the Wilmslow area," the force said in a statement.
"Enquiries in relation to the incident are in the early stages and no arrests have been made at this time."
Premier League champions City have so far declined to comment.
Walker has won four Premier League titles among nine major trophies since joining from Tottenham in 2017.
The 32-year-old has been capped 73 times by England.
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