King was drafted by St Kilda with their first selection which was the fourth overall in the
2018 national draft. Twin brother Ben was also drafted that year, by the
Gold Coast Suns with six. The King brothers were the first twins to both be drafted in the top 10. In June, King sustained a right ankle injury while playing for Sandringham which prevented him from making his AFL debut in 2019. Overall, King played five VFL games and kicked 11 goals.
2020 season King made his AFL debut in St Kilda's round one match against
North Melbourne. King played 18 of a possible 19 games for the Saints in a
COVID-interrupted season and finished with 22 goals and two finals appearances. For season 2020, King was also St Kilda's second-highest goal scorer, finishing behind
Dan Butler (29 goals), and equal-first for contested marks with
Rowan Marshall. King was also selected in the AFL's
22under22 at full forward.
2021 season A golfing incident saw King miss round one with a concussion injury, but he returned to the side in Round 2 and kicked 2 goals against Melbourne. King then had a poor run of form in front of goal, kicking 11.21 (punctuated by a 5.2 effort against West Coast) including a disastrous 1.5 against Geelong in Round nine where he also had 10 marks. Public and media scrutiny of King was intense as a result, which included a St Kilda refusal to allow AFL great
Matthew Lloyd (his high school football mentor) to provide some coaching and technique advice to King. Max faced his brother for just the second time in Round eight, again at Carrara Stadium, with Max kicking 1.2 and having 13 disposals and five marks, while Ben kicked 3.1 from nine disposals and three marks; the Saints ultimately came from behind to win by nine points. However, King recovered from the poor form in the first half of the season to have a sensational second half. Following the Saints' bye in Round 14, King kicked 20.7. He had a career-best game in Round 19 against West Coast in Perth, kicking six goals and taking nine marks including eight contested inside 50 (a league record). King also finished ninth in the
Trevor Barker Award and earned the Best Emerging Player Award at the annual Best and Fairest. ==Statistics==