Graduating from Partizan's youth system, Vlahović made his first-team debut in 2016, winning a league title and two Serbian Cups.

After an impressive goalscoring form in the first half of 2021–22, Italian rivals Juventus signed him in January 2022 for a reported fee of €70 million.

Shortly after, he joined OFK Beograd's youth system for three months, and also made one appearance for Red Star Belgrade.

[8] On 2 April, Vlahović scored his first career goal for Partizan against Radnik Surdulica in a 3–2 home victory, and became the youngest scorer in club history.

[10] He was scouted by multiple established European teams, including Arsenal, Anderlecht and Juventus with Partizan declining all offers.

[30][31] On 22 December 2020, he contributed with a goal to Fiorentina's away win in Turin over Juventus (3–0), which marked the first victory of the Viola at the home of the Bianconeri after 12 years.

[22][39] Fiorentina president, Rocco Comisso in an interview later remarked of Vlahović' agents: "it was clear to everyone they already had a deal with someone...", alluding that his entourage had already given a secret agreement with Juventus in the months prior.

[44] On 16 April, Vlahović became the second-youngest non-Italian player to score 50 goals in Serie A, after Alexandre Pato, with his late equaliser in a 1–1 draw against Bologna.

[46] Despite losing the final, Vlahović finished as the top scorer of the competition with four goals, with the other three being scored during his time with Fiorentina.

[47] Five days later, he scored his 24th goal of the season in the 2–2 home draw against Lazio, to become the highest-scoring Serbian footballer in Serie A history, alongside Dejan Stanković.

However, having recovered halfway through the season, he scored Juventus' goal in a 1–1 home draw against Nantes in the Europa League play-off round.

[55] Vlahović was a member of the Serbia national under-15 team,[56] scoring a hat trick in a match against the Czech Republic on 16 April 2015.

[58] In August 2016, Vlahović was called up to the under-19 squad for the Stevan Vilotić memorial tournament, where he debuted in the opening match against the United States.

[61] On 11 October 2020, Vlahović debuted for the Serbian senior team in a 2020–21 UEFA Nations League game against Hungary.

[63] On 12 October 2021, Vlahović embarked on a prolific goalscoring form for his national team with his four goals, including a brace against Azerbaijan, proving to be crucial as Serbia secured qualification to the 2022 FIFA World Cup on top of their qualifying group ahead of the former European champions, Portugal, after defeating them 2–1 away from home.