The former Dunedin bowler, who now plays for the Tweed Heads Club in Australia, lost to Black Jack Shannon McIlroy (Stoke) 21-11.
Girdler (51) has always used his weighted shots to get him out of difficulties in games, but it did not work for him.
His draw play was sound but he missed all his drives and run shots when McIlroy dominated the head.
McIlroy (29) missed the only drive he played in the game but was consistent on the draw and always had bowls close to the jack.
McIlroy, who won a gold and bronze medal at the Asia-Pacific championships last month, first played for the Black Jacks in 2007, but this was the Nelson bowler's first national open championship title.
McIlroy took an early advantage when he scored four on the eighth end to lead 10-4, but Girdler fought back by scoring six shots on the next four ends to trail 11-10 after 12 ends.
McIlroy took a strong grip on the game by scoring seven shots from the 13th to the 16th ends to lead 18-10. He completed the game with a two on the 18th end and one on the 19th end.
McIlroy scored points on 12 ends and Girdler on only seven.
Kelsey Cottrell (St Johns Park) was born in Auckland and came back to New Zealand to win the women's singles title when she beat Tayla Bruce (Burnside, Christchurch) 21-15 yesterday.
Cottrell (25) has played 284 tests for Australia in the past 10 years and won gold medals in the pairs and fours at the Asia-Pacific championships.
She demonstrated the ability to play the telling shot at the decisive moment to get the better of her younger opponent.
This occurred on the 17th end when Bruce had three shots on the head that would have levelled the scores at 18-18. The accurate Cottrell gained two shots with her last bowl to lead 20-15 and scored the winning shot on the next end.
Both bowlers scored on nine ends but what proved decisive was Cottrell's ability to score four points on the seventh and 14th ends.
Bruce (20), a primary school teacher student at Canterbury University who made her debut for the Black Jacks in the Trans Tasman series at the end of last season, was playing in her second national singles final in three years.
Bruce showed she has the temperament to play at World Bowls by fighting back when Cottrell led 12-4 after eight ends.
When Bruce took the jack she upset Cottrell's rhythm by playing short ends.
It worked as she scored eight shots on the next five ends to level the scores at 12-12.
When Cottrell got control of the jack again she played long ends to score nine points on the last five ends to win the game.
Skip Mandy Boyd made some telling shots that made the difference when the defending champions retained the pairs title they won in Auckland last year.
Burnside sisters Mandy and Angela Boyd beat the Victoria club's mother and daughter combination of Leigh and Kirsten Griffin 17-10 in the women's event.
Angela had the edge with the lead bowls and Mandy added the scoring shots.
They both shaded their opponents.
The scores were level at 5-5 after seven ends and 10-10 after 14 ends.
The Boyds then took control to score a two, four and one on the next three ends to win the game.
The father-and-son combination of Neville and Ali Forsyth had a comfortable 20-11 win over the Australian pair of Greg Dale and Andrew Howie.
The Australians struggled at the start and were down 10-0 after just five ends.
It was catch-up bowls for them after that and their only bright spot came on the 10th end when they scored five shots to trail 12-8.
The Forsyths tightened their game after this and scored eight shots on the final seven ends to win the game.
Neville Forsyth had the better of Dale with the lead bowls and his son made some excellent conversion shots and drove them out of trouble when it was needed.
NZ championships
The finals
SINGLES
Men: Shannon McIlroy (Stoke) 21, Paul Girdler (Tweed Heads) 11.
Women: Kelsey Cottrell (St Johns Park) 21, Tayla Bruce (Burnside) 15.
PAIRS
Men: Neville and Ali Forsyth (Composite) 20, Greg Dale, Andrew Howie (Composite) 11.
Women: Angela and Mandy Boyd (Burnside) 17, Kirsten and Leigh Griffin (Victoria) 10.
