He reached the final of the 2015 Amateur Championship where he lost 4&2 to Romain Langasque and played in the Walker Cup later the same year.

Forrest made his professional debut at the 2016 Alfred Dunhill Links Championship, finishing tied for 41st place.

[3] The following month he lost to Stuart Manley in a playoff in the Hauts de France Golf Open, after making a bogey at the third extra hole.

[4] He was runner-up for the third time in the Hainan Open in October and finished 7th in the Order of Merit to earn a place on the 2019 European Tour.

[6] The following month he won the Hero Open by one stroke from James Morrison, finishing with two birdies at the last two holes.