Mahzari began his career at the youth team of Al-Ettifaq. On 11 October 2020, Mahzari signed his first professional contract with Al-Ettifaq.[3] On 25 August 2022, Mahzari joined Saudi First Division League side Al-Shoulla on a one-year loan.[4] On 14 August 2023, Mahzari made his debut for Al-Ettifaq as a substitute in the 2–1 league win against Al-Nassr.[5] On 4 November 2023, Mahzari made his first start for the club in the 0–0 draw against Al-Raed.[6] On 31 January 2024, Mahzari renewed his contract with Al-Ettifaq before joining Pro League side Al-Taawoun on a one-and-a-half year loan.[7] He made his debut for Al-Taawoun on 23 February 2024 as a substitute in the 3–1 win against Al-Okhdood.[8] On 3 May 2024, Mahzari was substituted off the pitch after getting injured in the league match against Al-Hilal. Later, it was announced that he had injured his ACL and would undergo surgery.[9]
