Having led 3-1 early on in his third successive European Tour final thanks to a 170 finish and been in front for all of the match, White looked to have spurned a glorious opportunity as his opponent threw a 104 finish to edge ahead at 7-6.
But White levelled with his final dart at double before dominating the final leg, one in which Wright failed to apply any kind of pressure, and hitting double 16 for the title.
One week on from a last-leg defeat to Michael van Gerwen in the final of the Austrian Darts Open, White picked up his second European Tour title, the first having come just last September in the Netherlands.
This was also Diamond's fourth PDC final of the season having also lost to MVG at the German Darts Open last month and Players Championship Three back in February - so it may have come as some relief when Wright knocked out the world number one in the quarter-finals.
Snakebite triumphed 6-3 in an entertaining clash which saw him gain revenge for the 8-1 pummelling he received in Thursday night's Premier League Darts clash in Sheffield.
Wright, who had averaged 104.75 in beating Jonny Clayton 6-4 earlier in the day, then took care of Jamie Hughes 7-1 in the last four but just fell short in his bid to win his first final of the campaign.
White had beaten Keegan Brown 6-3 and Jeffrey De Zwaan 6-1 on Sunday, before rattling off three legs in succession to edge past Steve Beaton, who was playing in his first European Tour semi-final since September 2017.
Diamond had survived match darts against Dimitri Van den Bergh on Saturday until again calling on those extra reserves to fend off Wright, a 170 finish in leg four the highlight before he dug deep when it mattered.
Sunday results
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Afternoon Session (1200 GMT)
Third Round (Best of 11 legs)
- Ian White 6-3 Keegan Brown
- Jeffrey de Zwaan 6-4 Michael Smith
- Steve Beaton 6-4 Ryan Searle
- Darren Webster 6-4 Gerwyn Price
- Nathan Aspinall 6-4 Daryl Gurney
- Jamie Hughes 6-4 Mark McGeeney
- Peter Wright 6-4 Jonny Clayton
- Michael van Gerwen 6-1 James Richardson
Evening Session (1815 GMT)
Quarter-Finals (Best of 11 legs)
- Ian White 6-1 Jeffrey de Zwaan
- Steve Beaton 6-2 Darren Webster
- Nathan Aspinall 5-6Jamie Hughes
- Peter Wright 6-3 Michael van Gerwen
Semi-Finals (Best of 13 legs)
- Ian White 7-5 Steve Beaton
- Jamie Hughes 1-7 Peter Wright
Final (Best of 15 legs)
- Ian White 8-7 Peter Wright
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