Alexander-Arnold joined Liverpool's academy in 2004 and captained the club across its youth levels. He made his senior debut in 2016, at age 18, and played in back-to-back UEFA Champions League finals in 2018 and 2019, winning the latter and being named in the Champions League Squad of the Season. These appearances made Alexander-Arnold the youngest player to start in consecutive finals in the competition. In the same year, he won the UEFA Super Cup and the FIFA Club World Cup. In domestic football, he won the 2019–20 PFA Young Player of the Year and the inaugural Premier League Young Player of the Season awards, has twice been named in the PFA Team of the Year, and helped end Liverpool's 30-year league title drought by winning the 2019–20 Premier League.