Finn is a 3rd generation Hawk as his father and grandfather played football with the club.

Maginness played for the Sandringham Dragons in 2019 and also represented Vic Metro in four games across that year's national carnival.

Hawthorn secured Maginness under the father–son rule, after matching North Melbourne's bid with Pick 29 in the 2019 AFL Draft.

He showed promise during the pre-season games and with scratch matches against other AFL clubs.

[3] Throughout 2022 and 2023, Maginness evolved into a tagging role, and quickly became one of the best taggers in the league, shutting down players such as Josh Kelly (Australian footballer), Touk Miller, and Clayton Oliver.