Labanauskas, who famously defeated Raymond van Barneveld last month at the William Hill World Darts Championship, clinched glory in Hildesheim with a final victory over another Dutchman in Vincent Van der Meer.
The Lithuanian joined Niels Zonneveld, Mike Van Duivenbode and Christian Bunse in winning Tour cards outright with tournament triumphs during the four-day event, which had 249 entries.
Labanauskas' last chance at securing full-time status on the PDC circuit for the next two years began with early wins against Hendrik Eggermann, Day three finalist Pavel Jirkal and Germany's Sebastian Pohl.
He then defeated Portuguese ace Jose De Sousa to reach the last 16, where he got the better of Belgian youngster Kenny Neyens 5-3.
A quarter-final whitewash over France's Thibault Tricole set up a semi-final meeting against Latvian star Madars Razma, which Labanauskas won 5-2 with an average of over 96.
The 42-year-old then sealed his Tour card by taking out 80 to complete a 5-3 success against Van der Meer.
"It was really difficult because I knew if I lost a game then I wouldn't get my Tour Card," said Labanauskas.
"I came into today knowing I needed only to win and I was able to do that. I'm very happy."
Van der Meer enjoyed opening victories against Francesco Raschini, Roxy-James Rodriguez, Wesley Bour and John Michael to reach the quarter-finals.
There, he defeated compatriot Toon Greebe 5-3 to set up a meeting with another countryman in Yordi Meeuwisse - who he beat by the same the margin.
There was disappointment in the final for Van der Meer but his performances over the four days left him a strong position to secure a Tour card after finishing fourth on the final Order of Merit.
The Order of Merit was topped by Razma - a Players Championship finalist in 2018 - sealing a Tour card for the Latvian.
Further PDC Tour Cards will be awarded following the completion of the UK Qualifying School to players from both the UK and European Q School Orders of Merit, on a pro-rata basis in relation to tournament entries.
2019 PDC European Qualifying School
Day Four, Sunday January 6
Last 16
- Toon Greebe 5-2 Rene Eidams
- Vincent Van der Meer 5-3 John Michael
- Jyhan Artut 5-3 Lukasz Waclawski
- Yordi Meeuwisse 5-0 Marko Kantele
- Darius Labanauskas 5-3 Kenny Neyens
- Thibault Tricole 5-2 Pauli Finnila
- Kevin Munch 5-2 Pascal Wirotius
- Madars Razma 5-3 Mareno Michels
Quarter-finals
- Vincent Van der Meer 5-3 Toon Greebe
- Yordi Meeuwisse 5-2 Jyhan Artut
- Darius Labanauskas 5-0 Thibault Tricole
- Madars Razma 5-2 Kevin Munch
Semi-finals
- Vincent Van der Meer 5-3 Yordi Meeuwisse
- Darius Labanauskas 5-2 Madars Razma
Final
- Darius Labanauskas 5-3 Vincent Van der Meer
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