Hajdari first played for local club FC Aesch and moved to Basel's youth academy in 2014. He joined FC Basel's first team directly from their U-18 team for their 2020–21 season under head coach Ciriaco Sforza. Somewhat surprising came the announcement on 19 September that Juventus had bought the rights of the young right back defender Hajdari. But Hajdari stayed with the squad, being loaned back to Basel for two seasons.[1][2]
Hajdari played his professional debut for the club in the away game on 27 September as Basel were defeated 1–0 by Servette. The winning goal was scored from the penalty spot, the penalty was caused as the ball was headed from very close range onto Hajdari's upper right arm.[3] On 15 July 2021, Juventus announced the termination of the loan one year early.[4] However, he did not play any matches with the Juventus U-19. On 4 January 2022, he returned to the Swiss club on a six-month loan.[5]
During his time with Basel's first team, Hajdari played a total of 24 games for them scoring one goal. Nine of these games were in the Swiss Super League, and 15 were friendly games. He scored his only goal during the test game on 12 January 2022 as Basel beat Lugano 2–1.[6] During his time on loan to Basel, Hajdari also had five appearances in their U-21 team in the third tier of Swiss football.[7]