In Dekker's PDC World Championship debut he was beaten 3–0 by two-time winner Adrian Lewis. He lost 6–5 to Andrew Davidson in the opening round of the 2016 UK Open. Dekker reached the third round of the European Darts Open by defeating John Henderson 6–4 and Dave Chisnall 6–3, but was thrashed 6–0 by Gary Anderson. Dekker made his debut in the Players Championship Finals after being placed 54th on the Order of Merit and beat Steve West 6–3 in the first round, before losing 6–1 to Justin Pipe.