is a British professional footballer who plays as a right-back for Serie A club AC Milan, on loan from Premier League club Manchester City, and the England national team.

Walker started his career at his boyhood club Sheffield United at the age of seven. He made his first-team debut aged 18 after a loan spell at Northampton Town. He impressed whilst playing for United and played in the 2009 Championship play-off final. His performances earned him a move to Premier League club Tottenham Hotspur, before being immediately loaned back to Sheffield United. After further loan spells at Queens Park Rangers and Aston Villa, Walker cemented his place in Tottenham's first team. He was part of the Tottenham team coached by Mauricio Pochettino that finished runner-ups in the 2016–17 Premier League and 2014–15 League Cup.

Walker joined Manchester City in 2017 for a fee of £45 million. Throughout his City career, he has been coached by Pep Guardiola. With City, he has won six Premier League titles, four EFL Cups, two FA Cups, and a UEFA Champions League in 2023 as part of a continental treble. He has been named in the PFA Team of the Year four times, in the 2011–12, 2016–17, 2017–18 and 2023–24 seasons. He was loaned out to Milan in January 2025.

Walker played for England at under-19 and under-21 levels before making his debut for the senior national team in September 2011. He has represented England at three UEFA European Championships, in 2016, 2020 and 2024, and at two FIFA World Cups, in 2018 and 2022.