PRAGUE, 30 Aug 2015, (AFP) - The 23-year-old from Antwerp came into the final day with a one shot lead and kept his nerve down the stretch with a rock solid three under par round of 69 to finish on 20-under and relegate Sweden's Pelle Edberg into second.
Englishman Matthew Fitzpatrick carded an excellent final round of four under 68 to lie alone in third place, four shots behind the champion.
"I can't really explain it right now, it's stuff you dream about but I've worked really hard and it's great to get this first win under my belt so early in my career," said the big-hitting right hander.
"My family drove all night to be here even if I told them not to come because I thought it might make me nervous but it's great that they're here.
"I tried to stay calm early in the round even after I made double bogey (at the third) but I managed to regain my focus. Coming down the stretch over those last couple holes, I was pretty nervous but we're going to celebrate tonight (Sunday)," he added.
Englishman Robert Dinwiddie came home fourth on 14-under and six back while three players including Italian Renato Paratore, Roope Kakko of Finland and Denmark's Thorbjorn Olesen were a further three strokes back and tied for fifth.
Frenchman Gregory Bourdy had one of the best rounds of the day and climbed into a tie for eighth on 10-under following a five under 67.
Formerly known as the Czech Open, the tournament became the Czech Masters in 2014 and is played at the lush par-72 Albatross Golf Club in Prague.
Leading scores after the fourth and final round of the EPGA Czech Masters on Sunday at the Albatross Golf Resort - par 72 - in Prague:
268 - Thomas Pieters (BEL) 66-68-65-69
271 - Pelle Edberg (SWE) 66-67-67-71
272 - Matthew Fitzpatrick (ENG) 66-67-71-68
274 - Robert Dinwiddie (ENG) 69-67-68-70
277 - Thorbjorn Olesen (DEN) 67-69-67-74, Roope Kakko (FIN) 67-72-68-70, Renato Paratore (ITA) 65-73-70-69
278 - Damien McGrane (IRL) 69-70-71-68, Gregory Bourdy (FRA) 70-70-71-67, Eduardo De La Riva (ESP) 65-76-69-68, Kristoffer Broberg (SWE) 67-73-69-69, Craig Lee (SCO) 68-71-69-70
279 - Rikard Karlberg (SWE) 70-68-71-70, Sam Hutsby (ENG) 66-70-71-72, Gary Boyd (ENG) 69-72-69-69, Connor Arendell (USA) 72-67-71-69
280 - Peter Uihlein (USA) 70-71-66-73, Anthony Wall (ENG) 72-70-67-71, Graeme Storm (ENG) 70-73-71-66, Mikael Lundberg (SWE) 72-71-64-73, Jaakko Makitalo (FIN) 71-70-68-71
281 - Marcel Schneider (GER) 72-67-71-71, Joakim Lagergren (SWE) 69-73-69-70, David Lipsky (USA) 71-69-68-73, Eddie Pepperell (ENG) 69-68-71-73, Michael Hoey (NIR) 67-70-71-73