[3][4] He was chosen to represent the Australian Schoolboys rugby league team in 2019, scoring a try and earning the player of the match award in a win against New Zealand.

[6] In June 2022, Howarth was selected for the Queensland U19s junior State of Origin team for their match against NSW.

[7] After two seasons playing with the Sunshine Coast Falcons in the Queensland Cup where he often struggled with injuries that hampered his development,[5] Howarth made his NRL debut in round 27 of the 2023 NRL season for the Melbourne Storm against the Brisbane Broncos at Suncorp Stadium.

[6] Howarth had an extended run in the Melbourne Storm squad during the 2024 season, earning a starting role in the centre position and scoring his first NRL try.

Howarth played a total of 16 matches for Melbourne in the 2024 NRL season as the club were runaway minor premiers.