Theatre career
Shkumbin Istrefi began his professional theatre career after completing his acting studies at the Faculty of Arts in Prishtina, where he trained in the class of actor Enver Petrovci and graduated in 1994. He went on to perform in numerous productions at Dodona Theatre and the National Theatre of Prishtina, contributing to the development of Kosovo's live stage scene during the post-graduation phase of his career.

His involvement with the National Theatre of Prishtina extended beyond performing when, on July 15, 2011, he was appointed as a member of the Steering Council of the National Theatre of Prishtina in his capacity as an actor representative. This role underscored his standing within Kosovo's theatre community and his commitment to institutional governance in the performing arts.

Television career
Shkumbin Istrefi has made substantial contributions to Kosovo television, most prominently through his central role in the long-running sitcom Kafeneja Jonë. He co-created the series, served as its producer and executive producer alongside Mentor Shala, directed numerous episodes from 2007 to 2013, and starred as the character Fekë Bobaj, commonly known as Feka. Broadcast on Radio Television of Kosovo (RTK), the show ran from 2004 to 2013 with approximately 359 episodes, becoming one of the most popular programs in Kosovo during its run.

In addition to his extensive work on Kafeneja Jonë, Istrefi has taken on acting roles in other television series. He appeared as Azem in one episode of Prespav and as Mentor Pirulli in episodes of Rrushe.

Istrefi also directed the television series 3 Vllaznit (also known as Tre Vllaznit), serving as its main director. His involvement in these projects highlights his versatility across acting, directing, and producing in Kosovo's television landscape.

Film career
Shkumbin Istrefi has established himself as a prominent actor and producer in Kosovar and regional cinema since the mid-2000s. His acting career in feature films began with the role of Gafurri in Kukumi, a notable Kosovar drama directed by Isa Qosja. He appeared as the Gypsy driver in Lindje, perëndim, lindje (East, West, East: The Final Sprint), directed by Gjergj Xhuvani, and also served as co-producer on the project. He followed this with the role of Lilushi in Gomarët e kufirit (Donkeys of the Border).

Throughout the 2010s, Istrefi continued to take on diverse supporting and character roles in independent films. He portrayed Bashkim in Home Sweet Home, a Macedonian-Kosovar production directed by Faton Bajraktari. He played a Taxi Driver in Unwanted, directed by Edon Rizvanolli. His credits include Syla in Field of Blackbirds, directed by Arzana Kraja, and Dino in Cirku Fluturues. He also appeared as Xhinga in An Unforgettable Spring in a Forgotten Village, directed by Kushtrim Bekteshi.

In more recent years, Istrefi has remained active in cinema. He portrayed Jasemi in The Stork, directed by Isa Qosja, and the Father in the short film SOS, directed by Anita Morina. Beyond acting, Istrefi has contributed as a producer to several acclaimed Kosovar films. He served as producer on Three Windows and a Hanging, directed by Isa Qosja, which received critical praise. He also produced Vera Dreams of the Sea, directed by Kaltrina Krasniqi, another critically well-received work.