Born in Russell, Ontario to a Brazilian mother and a Jamaican father, Walker moved to Belgium at age six with his family, before later moving back to his hometown in Canada three years later.[1][2] Walker played youth soccer with the Ottawa St. Anthony Futuro Academy.[3] In 2022, after being spotted by scouts from Atlético Ottawa, he participated in Atlético Ottawa's Atlético de Madrid Development program.[3][4]
In 2023, he was invited to attend pre-season with Canadian Premier League club Atlético Ottawa, where he scored in a friendly against Spanish Primera Federación side UD San Sebastián de los Reyes.[7][8] In April 2023, he signed a U Sports contract with the club, which allows him to maintain his university eligibility.[9] He made his professional debut on May 13 as a late game substitute.[10] On August 2, with his U Sports contract set to soon expire, he signed an extension for the remainder of the 2023 season.[11][12] Following his first professional start on August 13 against Pacific FC,[13][14] he was named to the CPL Team of the Week for the first time.[15] After the season, he signed a professional contract with the club for the 2024 and 2025 seasons.[16][17] Ahead of the 2025 season, he went on a training stint with their affiliate club in Mexico Atlético San Luis.[18]