Ayr United Forrest made his debut for
Ayr United in a
Scottish Challenge Cup match against
Queen's Park. He came off the bench to score an 89th-minute winner at
Hampden Park. With this goal Forrest became Ayr's youngest ever goalscorer aged 16 years, 321 days. During the
2019–20 Scottish Championship season, Forrest was awarded the
Scottish Championship Player of the Month for September after scoring five goals in three league games.
Livingston Forrest signed a pre-contract deal with
Livingston on 10 April 2020, making the jump from the
Scottish Championship to the
Scottish Premiership. Forrest made his debut for Livingston on the opening day of the
2020–21 Scottish Premiership season in a 1–0 loss against
St Mirren at
St Mirren Park. He scored his first goal for Livingston in a 2–2 draw against
Motherwell on 12 August 2020, at
Fir Park.
Heart of Midlothian On 1 June 2022, it was announced that Forrest would join
Scottish Premiership side
Heart of Midlothian on a two-year deal, following the expiry of his Livingston contract on 10 June. On 19 January 2024, he signed a two-year extension to his contract until 2026. == International career ==