The 2021 Royal London One-Day Cup tournament was a limited overs cricket competition that formed part of the 2021 English cricket season in England and Wales. Matches were contested over 50 overs per side, having List A cricket status, with all eighteen first-class counties competing in the tournament. The tournament started on 22 July 2021, with the final taking place on 19 August 2021 at Trent Bridge in Nottingham. Somerset were the defending champions winning the 2019 tournament, with no tournament taking place in 2020 due to the COVID-19 pandemic.