Topić grew up playing basketball for KK Defense from his native Novi Sad from which he joined the Crvena zvezda youth system in June 2020.

[1][2] On 28 March 2022, Topić made his professional debut for Crvena zvezda in an ABA League match against Slovenian side Krka at the age of 16.

At 16 years, seven months and eighteen days of age, he became the youngest player in club's history to score points for Crvena zvezda in the ABA League.

[7] He returned to Crvena zvezda shortly after, and played with the team from October until December of the same year, during which in limited role he averaged 3.4 points over seven ABA League games.

[19] In August 2021, Topić was a member of the Serbian under-16 national team that participated at the FIBA U16 European Challengers in Novi Sad, Serbia.

[22] A power forward, Milenko spent most of his career in the YUBA League playing for Profikolor, BFC Beočin, Crvena zvezda as well, Budućnost and Hemofarm.