Uno made his senior ISU Championship debut at the 2015 Four Continents; he placed second in the short program, fifth in the free skate, and fifth overall, setting personal best scores in all segments. He ended his season by winning the 2015 World Junior Championships, winning the short program with a junior world record score of 84.87 and placing second in the free skate. He became the fifth Japanese man to win the junior world title.