His father attempted to mold him after Croatian basketball player Drazen Petrovic and enrolled his son at the Australian Institute of Sport (AIS).

[3][4] He helped Lake Ginninderra win the national title at the 2015 Australian schools championships alongside teammate Jack White.

[5] Vasiljevic was recruited by Stanford, LSU, Louisville, and California, but he signed with Miami because he liked the academics and his family loved the city.

[8] On 21 November 2019, he scored a career-high 25 points including the two clinching foul shots with 1.2 seconds remaining in a 74–70 win over Missouri State.

[11] After going undrafted in the 2020 NBA draft, Vasiljevic signed with the Sydney Kings of the National Basketball League (NBL) on 17 July 2020.

[13] In the 2022 off-season, Vasiljevic played for the Phoenix Suns in the NBA Summer League[15] and the Diamond Valley Eagles in the NBL1 South.

[13] Vasiljevic played for the Washington Wizards in the 2023 NBA Summer League[18] and then joined the team for a brief pre-season stint.

[26] He won a silver medal at the 2014 FIBA Under-17 World Championship in Dubai and was named to the all-tournament team after averaging 17.4 points and 6.6 rebounds per game.