Amario Cozier-Duberry was born on 29 May 2005 in London and grew up in Tottenham. After being passed over by several local clubs, he joined grassroots side Chettle Court Rangers before earning a trial at Arsenal. He permanently joined Arsenal's Hale End academy in October 2019 at the age of fourteen, signing his first professional contract with the club in June 2022.
Cozier-Duberry left Arsenal in the summer of 2024 without making a competitive first-team appearance, joining Brighton & Hove Albion on a free transfer. He spent the 2024–25 season on loan at Blackburn Rovers in the Championship, making 22 league appearances and scoring once. He then joined Bolton Wanderers on loan in League One for the 2025–26 season, where he made a stronger impression — winning both EFL League One Player of the Month and EFL Young Player of the Month for October 2025 and earning a place in the League One Team of the Season.
A left-footed winger with an eye for cutting inside, he has drawn comparisons to Bukayo Saka and Moussa Diaby. A knee ligament injury in January 2026 interrupted a promising campaign, though he returned in April and scored twice in a 5–1 win over Stevenage shortly after. He has been nominated for EFL League One Young Player of the Season for 2025–26.
At international level, Cozier-Duberry has represented England across youth age groups from under-16 to under-20, making his England U20 debut in March 2025. Brighton hold him on a four-year contract, viewing him as a prospect for their first team.