Born in
Solothurn, Avdullahu started his youth football with local club FC Gerlafingen and then moved to
Solothurn in 2013. In the summer of 2018, he moved to
Basel's youth department and in 2022 he advanced to their U-21 team, but remained part of the U-18 team that celebrated winning the Swiss championship at the end of June 2023. In July 2023 he signed his first professional contract and advanced to their first team for their
2023–24 season. After playing in three test games Avdullahu played his
domestic league debut for the club in the home game in the
St. Jakob-Park on 13 August 2023 as Basel were defeated 2–1 by
Lausanne-Sport. In the
2023–24 Swiss Cup second round match, on 16 September, Avdullahu scored his first goal for the team as Basel went on to win 8–0 against amateur club FC Bosporus in
Bern. As
Fabio Celestini became FCB head-coach, Avdullahu became a regular starter. He scored his first league goal for the team on 30 March 2024 in the home game in the
St. Jakob-Park as Basel played a 2–2 draw with
Zürich. At the end of the
2024–25 Swiss Super League season he became Swiss champion and Cup winner with them. On 12 June FC Basel 1893 announced that their former youth player Avdullahu was moving to
TSG 1899 Hoffenheim in the German
Bundesliga. During his two seasons with FCB's first team, Avdullahu played a total of 71 games for them scoring a total of three goals. 63 of these games were in the
Swiss Super League and 8 in the
Swiss Cup. He scored two goals in the domestic league and the other in the cup. On 12 June 2025, German
Bundesliga side
TSG 1899 Hoffenheim announced the signing of Avdullahu on a long-term contract. ==International career==