Henderson, who turns 18 on Sept.
10, stormed to victory by a staggering eight shots at the Cambia Portland Classic in Oregon, a closing three-under 69 giving her largest winning margin on the circuit this season.
Henderson emulated New Zealand’s Lydia Ko and American Lexi Thompson as LPGA winners before turning 18. Ko was 15 when she first won, while Thompson was 16.
“After reviewing Brooke Henderson’s petition, I have granted her LPGA Tour membership beginning immediately,” LPGA commissioner Michael Whan said in a statement.
“Brooke truly earned her card, and we are looking forward to Brooke joining our Tour and our family. She is a special player and a wonderful person.”
The LPGA Tour has an 18-year-old age requirement for membership but commissioner Whan can waive the rule, as he did in 2011 for Thompson and two years later for Ko.
“Since I was a little girl in Smiths Falls, Ontario, my dream has been to play on the LPGA Tour,” said Henderson, who will be competing this week at the Canadian Pacific Women’s Open at Vancouver Golf Club.
“I am so grateful for the opportunity to join the Tour as a member and play alongside so many of my role models.
“Realizing this dream here at the Canadian Pacific Women’s Open in my native Canada is even more amazing and I am so proud to be an ambassador for golf in this amazing country.”
Henderson, ranked 17th in the world, has won $661,818 in unofficial earnings on the LPGA Tour this year after 10 events, through sponsor exemptions and Monday qualifying.
She began playing golf at the age of three and won her first tournament on the Canadian Women’s Tour at the age of 14.
Henderson was a runner-up at the 2014 U.S. Women’s Amateur and has recorded consecutive top-10s at the U.S. Women’s Open – joint 10th in 2014 and tied for fifth this year.
(Reporting by Mark Lamport-Stokes in Los Angeles; Editing by Andrew Both)