The 17-year-old will headline the international field coming to the Clearwater Golf Club for the sixth staging of the tournament from February 27 to March 1.
Ko, who recently won for the third time this year on the LPGA Tour to claim the Race to the CME Globe points race in her rookie season, will look to capture her second national open title.
"There is nothing like playing in front of my home fans and this makes this tournament one of my favourite events of the year," Ko said.
"I can't wait to be back home with some good friends and family and hopefully have a chance to win my national open for a second time."
Ko won her first national crown in 2013 and looked like she would go back-to-back this year, however a course-record 63 by South Korean Mi Hyang Lee saw Ko finish second by just one shot.
It's a huge boost for New Zealand Golf to have Ko support her national open, which is a co-sanctioned event on the Ladies European Tour and the Australian Ladies Professional Golf Tour.
"This is wonderful news for the New Zealand Women's Open and for golf in general in New Zealand," said Dean Murphy, the chief executive of New Zealand Golf.
"Lydia is a fantastic ambassador for New Zealand on the world stage and it means so much to the golfing community that she has made coming home to play in her national open a priority."
Murphy said it wasn't an easy decision for the teenager as she was looking to get off to the perfect start on the LPGA Tour season with the Honda LPGA Thailand event that clashes with the Clearwater tournament, but he said her strong ties with New Zealand were key factors in the decision.
"Lydia loves coming home and she really appreciates the support she gets when she plays here. She is plying her trade on the LPGA Tour so this event doesn't help her in that regard, but she has shown her loyalty again to New Zealand and made a huge effort to be home," Murphy said.
Ko had a phenomenal maiden year on the LPGA Tour in 2014 picking up three victories, 12 additional top-10 finishes and was named the Rookie of the Year.
A high calibre field has once again been assembled for the 2015 New Zealand Women's Open. Three former champions: France's Gwladys Nocera, England's Laura Davies, and Australian Kristie Smith are confirmed starters, along with Ko.
All four players will be ones to watch, however the calibre of players is high with 15 LET Tour winners and three LPGA Tour winners in the field.
Players to also keep an eye on include Americans Cheyenne Woods, Beth Allen, Alison Walshe, Canadian Lorie Kane, England's Florentya Parker, South African Stacy Lee Bregman and Australians Stacey Keating, Nikki Campbell, Sarah Kemp and Smith.
