The 29-year-old went into Sunday's final round with a two-shot lead over playing partner Joakim Lagergren and maintained the same advantage despite a brilliant closing eagle from the Swede.
Syme finished 11 under, shooting a one-under-par 70 on Sunday and making only one bogey in his final 38 holes.
"Unbelievable, it was so, so difficult the last few days," said the Scot.
"I just felt so much better this week, I felt really ready to do it, and I'm so, so happy I managed to do it."
Wife Alanis flew out to Amsterdam to surprise Syme on the final green, where he also enjoyed champagne-drenched celebrations with compatriot Ewen Ferguson - who had a hole in one earlier in the day to help him finish in a tie for fourth - and England's Richard Mansell.
"It's so, so nice they stuck around," said Syme. "I've obviously been really pleased for them and I'm really happy to have joined them and won myself, so just amazing. Amazing."
Lagergren finished nine under, with South Africa's Jayden Schaper third on four under. Ferguson, fellow Scot Richie Ramsay and Englishman Jack Senior were a further shot back to share fourth.
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