She has won Ironman New Zealand three years in a row now and said she would return next year.
In parts of the race she knew she was really flying and in other parts of the race she found it extremely tough, she said.
"But that is the best I have felt in the marathon in probably two years."
Kiwi Gina Crawford finished seven minutes behind Meredith to claim second place.
It was the third time Crawford has finished second at the event.
Meanwhile, Estonia's Marko Albert held off challenges from Kiwi Ironman legends Cameron Brown and Terenzo Bozzone to win his first Ironman New Zealand title in Taupo.
Albert left the professional field in his wake during the 180km cycle before holding onto the lead in the 42km run.
He finished second last year but produced a great effort today to win his first ironman title.
"It was a little bit like last year. The same sort of thing happened but I felt a little bit better this year," he said.
"Today [I was given] a chance and I played the rabbit trying to run away from the lions."
The hungriest lion was Brown, who has won the event a record 10 times.
He pushed hard to try and pull Albert in during the run but could only manage to cut the lead down from six minutes to four minutes.
Bozzone finished in third.