Browning managed the top finish after completing the 400 metre swim, 16 kilometre cycle and 4km run course in a time of 55:08:00 minutes.
She faced a tough competition from Sherid Carter and Lucy McDonald, who finished second and third respectively.
Cook Islands Triathlon president Roland Neururer said they had a good number of entrance this year again, despite the weather.
“Harriet Browning and Sherid Carter came first out of the 400m swim together, with Sherid having a super-fast bike ride, and finishing about two minutes off Harriet after the 16km cycle,” Neururer said.
“But Harriet had the fastest run of the day and beat Sherid to win the women’s triathlon in a very good time of 55:08:00 minutes.”
Carter clocked 58:05:00 minutes followed by McDonald in a time of 59:08 minutes.
In the team event, team DDD with Kelly Pick (swim) Alyce Edwards (cycle) and Shannon Saunders (run) came home first and second overall in 57:14 minutes.
“CITAI would like to say a big thank to our major sponsor BSP Bank and our supporting sponsor The Bond Store, for some fantastic prices for all ladies,” Neururer said.
The first Tinman triathlon was held in April 1983 at the Sailing club in Muri with a 1200m swim, followed by a cycle around the island before running 10km from the sailing club to Banana Court for a well-earned drink.
The first person to cross the finish line back in 1983 was Paul McDonnell in a time of 2 hours and 9 minutes, ahead of Don Carlaw and Dave Hickson.