In 2017, Unterbuchner reached the last 48 of the World Masters. He qualified for the 2018 BDO World Darts Championship as one of the Playoff Qualifiers and played David Cameron in the preliminary round, winning 3–2. Unterbuchner became the first German player to reach a semi-final at a World Championship, as well as the first to win a last 16 match at a World Championship, when he caused an upset by beating No. 3 seed Jamie Hughes 3–2 in the first round, No. 14 seed Martin Phillips 4–2 in the second round, and No. 11 seed Richard Veenstra 5–4 in the quarter-final. Unterbuchner played No. 2 seed and BDO No. 1 Mark McGeeney in the semi-finals where he lost 4–6.
In 2020, Unterbuchner attended Q School but was unable to get a TourCard, He did however qualify for 2 PDC European Tour events, losing 6-4 to Darius Labanaukas & again 6-4 this time to Scott Baker.
Unterbuchner also took part in the German Super League where he qualified for the semi-final before losing 9-3 to Dragutin Horvat, with the event being won by Nico Kurz.
Unterbuchner won a PDC Tour Card for the first time during the PDC Q-School in February 2021. During his two-year adventure with the Professional Darts Corporation, he earned just only £4,000. At that time, he did not start in a televised tournament. In 2023, after losing the PDC Tour Card, he took part in the jubilee 2023 Dutch Open, confirming his return to competition in World Darts Federation tournaments.
World Championship results
BDO
2018: Semi-finals (lost to Mark McGeeney 4–6) (sets)
