Lawrie had earlier been crowned WDF Open Youth World Champion in Surrey, after beating Germany’s Florian Preis 4-2 in the first final of the day.
He said that victory, which made him the first Scottish winner of the trophy, meant “everything”.
Deta Hedman ended her long wait to win the women’s event for the first time.
Having lost each of her three previous finals in 2012, 2014 and 2016, Hedman, 66, defeated Dutch opponent Lerena Rietbergen 4-1.
Hedman’s triumph came in the absence of 2024 winner Beau Greaves, who has accepted a place in the PDC World Darts Championship, which starts on Thursday at Alexandra Palace.
Zehra Gemi became the first-ever Turkish darts world champion in the girls’ event.
The World Darts Federation-organised event is a 10-day knockout tournament, with open category champion Van Schie receiving the top prize money of £50,000.
