Kernaghan beat Jamie Hill (Auckland) 25-15 in the final. Hill had reached the semifinals in the previous two years but this was his first final.
The event was first held in 1990 and only two other bowlers have won it three times: Rowan Brassey (Auckland) and Shannon McIlroy (Nelson).
Kernaghan (61) first won the event in 1999 and his second win was two years ago in 2014.
``I'm excited,'' Kernaghan said. ``Any time you win an event with this quality of players you have got to be pleased.
``It was a good hit-out and I can go into World Bowls with a bit of confidence. That is my target. This win was a bonus for me.''
Kernaghan (61) lost his first two games at the tournament to fellow Black Jacks Shannon McIlroy (Nelson) and Australian-based Ali Forsyth on the first day.
After that, he won eight games on the trot to collect the winner's purse of $5,300. Hill won $2700.
``They are two of the best singles players ever in New Zealand and I had them first up,'' Kernaghan quipped.
Kernaghan has been practising hard for World Bowls but had little match play before the Speight's-sponsored event.
``It was a tough start but I managed to keep getting my nose in front in the other games and got better each day,'' he said.
It was neck and tuck in the final for the first 11 ends with the scores level at 8-8. Both bowlers drew accurately and were playing accurate nudge shots to score points.
The decisive moment of the game came on the 12th end when Kernaghan played a weighted shot with his last bowl to run the jack back when Hill had two shots on the head.
``Instead of 10-8 to Jamie it was 11-8 to me,'' he said.
Kernaghan backed this up on the next end when he nabbed four shots. Hill had two drives. He missed with the first and the second took out his own bowl and conceded four shots.
Kernaghan gained an eight-point cushion when he added one more shot on the next end when his first bowl nestled close to the jack.
He added two more points on the 16th end to lead 18-9 and this forced Hill to play catch-up bowls.
Kernaghan played a tight defensive game after this and restricted Hill to one, or at the most, two shots, on his good ends.
``That's the secret of singles,'' Kernaghan said. ``When you drop a shot don't drop them in big bundles.''
Hill had a solid three ends from the 17th to 19th ends to reduce the gap to five points.
This was broken on the next end when Kernaghan slid through a narrow gap to gain a toucher. He made 10 touchers in the game.
Hill had six drives and hit only one of them. Kernaghan was less aggressive and used weighted shots when he needed to shift bowls.
Kernaghan was accurate on the forehand and had the knack of rolling bowls in for points around the back of the front bowls.
In the other key games on the final day, Hill beat New Zealand World Bowls singles player Shannon McIlroy 25-23 in the quarterfinals and Kernaghan beat World Bowls team-mate Ali Forsyth 25-15 in the semifinals.
The rising star of the tournament was promising youngster Keanu Darby (20) from the host club who reached the semifinals.
He beat Andre Smith (Marlborough) 25-10 in the quarterfinal before losing the semifinal to Hill 25-10.
A delayed telecast of the final will be played on Southern Television's Channel 39 at the following times: Saturday, October 29 (7pm), Sunday, October 30 (1pm) and Tuesday, November 1 (3.30pm). The commentator is Dave Underwood.
