From Edinburgh, Whittaker came through the academy at Hibernian.[3] He signed his first professional contract with the club in August 2023.[4] He made his Scottish Premiership debut on 23 September 2023, as a second-half substitute for Hibernian against St Johnstone.[5] At 16 years and 44 days old he set a record as the youngest ever player to appear for the club.[6][7] Two days later he agreed a new three-year contract.[8] He made his first league start on 8 November 2023.[9]
On 9 August 2024, Whittaker returned to his childhood club Spartans on loan.[10]