At the Welsh Open he defeated world number 15 Robert Milkins 4–0 in the opening round, Tian Pengfei 4–1 and Oliver Brown 4–0. In the Pengfei match he made a break of 140, the highest in his professional career and ultimately the highest in the tournament. Furthermore, he would go on to beat reigning world champion and world number one Mark Selby in the fourth round after a deciding frame (4–3), having been 2–0 and 3–2 down, to reach the quarter-finals. There, Brecel met Ricky Walden, another top 16 player (ranked number 9 at the time). Brecel lost the first three frames, but he followed this up by winning the next five on the trot in order to reach the first ranking semi-final ever of his professional career. Four-time world champion John Higgins beat him 6–4. A pair of quarter-final exits in the European Tour events during the year saw Brecel finish 16th on the Order of Merit to make his debut in the Grand Final, where he lost 4–0 to Judd Trump in the opening round. His good season saw him climb 19 places in the rankings to end it at 44th in the world.