It was a formality, given Ko is already world No 5 and has won twice on tour, but it allows Ko to join the women's tour at the start of the 2014 season.
Last week Ko turned professional after announcing it in a quirky video with All Blacks fullback Israel Dagg and intends playing in next month's season-ending tournament in Florida.
She earned a spot in the tournament by winning the Canadian Women's Open, her second win on the LPGA Tour - she also won the 2012 Canadian Women's Open to become the youngest winner in LPGA history at 15 years, 4 months, 2 days.
"After reviewing Lydia Ko's petition, I have granted her LPGA Tour membership beginning at the start of the 2014 season," LPGA commissioner Michael Whan said in a statement. "This decision ensures that Lydia can attend all of our LPGA rookie development sessions that take place in the early part of the year.
"As for her exact playing status for the 2014 season, Lydia will compete out of category 7 on the 2014 LPGA Priority List. Category 7 is reserved for players who have won an official LPGA event as a non-member in the previous calendar year.
''We are looking forward to having Lydia as a full-time member for the 2014 season. It is not often that the LPGA welcomes a rookie who is already a back-to-back LPGA Tour champion."
Players aged between 15 and 18 can seek special permission to play on the LPGA Tour by petitioning the commissioner of the LPGA.
"I am very excited to become a member on the LPGA Tour," Ko said. "It has always been my dream goal to play on the LPGA, and play against the world's best players.
"I know that becoming a member is not only performing well, but to deal with responsibilities very well. Women's golf is growing day by day and I would love to be able to inspire other girls to take up the game, and go for it.
''I believe this is only the start to my career and I have many new things to learn along the way. I am so grateful to get the opportunity to play with the players I look up to and respect. I can't wait to start the season early next year."
