Grundy was born in Adelaide, South Australia and attended Cabra Dominican College, a private Catholic high school in the southern suburbs of the city, graduating in 2011.

[5] In 2018 he won the Herald Sun Player of the Year award with 27 votes, one clear of Melbourne ruck Max Gawn and Hawthorn midfielder Tom Mitchell.

[7] However, Grundy struggled to recapture his All-Australian form in subsequent years, with his salary criticised by some media figures.

In the latter half of the year he was dropped to the VFL to play with the Casey Demons and was not selected in either of Melbourne's finals games.

[citation needed] In December 2020, Grundy graduated from La Trobe University with a Bachelor of Health Sciences.