Džumhur began the new season in India, where he was unsuccessful in his bid to qualify for the main draw of the 2015 Aircel Chennai Open, losing to Luca Vanni in the final qualifying round. For the first time in his career, he also took part in the main doubles draw of an ATP World Tour level tournament, playing alongside Aljaž Bedene. Later in January he failed to pass Australian Open qualifying, after a three set loss to Tim Pütz in the second qualifying round, while being the top seed in the draw. After the Australian Open, Džumhur managed to win his first career singles match on ATP World Tour level in 2015 PBZ Zagreb Indoors, against Michael Berrer, in three sets, after saving two match points, before falling to third seed Guillermo García-López in two sets. It was also the first ATP 250 series tournament in Džumhur's career, where he was a direct acceptance, thus did not have to play qualifying event in order to be in the main draw.