Cullen's second ever PDC final came at the ninth Players Championship, but he was thrashed 6–0 by Benito van de Pas. Another came at the 11th event and he was left waiting for his first professional title as Ian White won 6–3. Cullen qualified for the World Matchplay for the first time in four years and lost 10–5 to Wright in the opening round. Cullen made his debut at the World Grand Prix and he won the first set against Simon Whitlock, before losing six of the next seven legs to bow out. After seeing off Chris Dobey 6–2 at the European Championship he was heavily beaten 10–3 by Phil Taylor in the second round. A 13 dart leg from Cullen saw him squeeze past Anderson in to the quarter-finals of the non-ranking World Series of Darts Finals, where he lost to Wright in a televised match for the third time in 2016, this time 10–7. Cullen eased past Steve Brown 6–1 and Rowby-John Rodriguez 6–0 at the Players Championship Finals, but then averaged 71.13 as Raymond van Barneveld knocked him out 10–2 in the third round.