NETHERLANDS, 13 Sept 2015, (AFP) - The 23-year-old, from Antwerp, becomes the first player since Rory McIlroy to win back-to-back EPGA starts after Englishman Lee Slattery blew a chance to send the championship to a playoff after missing a six-foot putt at the 18th.
Pieters finished with a winning score of 19-under par at the Kennemer Golf and Country Club in northern Holland.
Spaniard Eduardo De La Riva shot the day's joint-best score of 63 to share second spot with Slattery who was devastated after his final hole miss that ruined his chances of following on from his triumph at last week's Russian Open.
"I'm a little bit surprised because I was getting ready for the playoff," said the big-hitting Pieters.
"Lee (Slattery) played really well but this victory is even cooler than the first one and now I want number three.
"I was confident and just tried to tee it up. I missed a putt at the first hole and was a bit nervous, but I then made a couple of birdies and felt good after that. Now I'm going to go and celebrate with my family." he added.
Paraguayan Fabrizio Zanotti was alone in fourth after his 63 lifted him up the leaderboard while Englishman Eddie Pepperell and Denmark's Morten Orum Madsen were a further shot back on 16-under.
Spaniard Rafa Cabrella-Bello, who shared the overnight lead with Slattery, slumped to a final day 71 and a share of seventh place, while Scotland's 1999 British Open champion Paul Lawrie, who began the day one shot off the lead, also misfired with his 71 and finished tenth.
Leading scores after the fourth and final round of the Dutch Open on Sunday:
261 - Thomas Pieters (BEL) 68-66-62-65
262 - Eduardo De La Riva (ESP) 66-66-67-63, Lee Slattery (ENG) 66-65-63-68
263 - Fabrizio Zanotti (PAR) 67-66-67-63
264 - Eddie Pepperell (ENG) 67-66-67-64, Morten Madsen (DEN) 64-67-66-67
265 - Rafael Cabrera (ESP) 65-66-63-71, Mikko Korhonen (FIN) 67-70-65-63, Magnus Carlsson (SWE) 65-66-70-64
266 - Paul Lawrie (SCO) 61-71-63-71, Wade Ormsby (AUS) 61-68-68-69
267 - Soren Kjeldsen (DEN) 64-64-71-68, Alejandro Cañizares (ESP) 68-66-68-65, Michaël Lorenzo-Vera (FRA) 68-67-67-65, Maximilian Kieffer (GER) 67-67-64-69, David Howell (ENG) 68-69-63-67, Ben Evans (ENG) 68-67-65-67
268 - Andy Sullivan (ENG) 65-69-68-66, Matthew Nixon (ENG) 70-64-68-66, Tom Lewis (ENG) 69-65-65-69, Mikko Ilonen (FIN) 64-71-62-71, Jason Scrivener (AUS) 68-67-65-68
269 - Gregory Bourdy (FRA) 68-66-67-68, Simon Thornton (IRL) 67-68-66-68, Joost Luiten (NED) 63-71-68-67, Robert Dinwiddie (ENG) 67-70-70-62, Robert Rock (ENG) 63-69-71-66, Andrew Johnston (ENG) 66-68-65-70, David Lipsky (USA) 66-71-69-63