GALLOWAY, May 31, 2014 (AFP) - The 22-year-old American has one win on the LPGA tour, capturing the Mobile Bay LPGA Classic in 2013.
"I've been playing well the past few weeks, and so I felt pretty good about my game, and you know, if you just let it happen and just let a good round come together, normally it does," Johnson said.
Japan's Haru Nomura carded an eight-under 63 to sit alone in second place, while Christina Kim, of the United States, is in third at seven-under 64 at the Stockton Seaview Golf Club course.
World number one Park In-bee and Choi Na-Yeon shot matching five-under 66s to share fourth.
Park has been ranked number one for 59 straight weeks, but has yet to win a tournament this year.
She rolled in a 15-foot birdie putt at her opening hole to get her round off to a strong start.
"After I birdied the first hole, that really gave me a lot of confidence going into the rest of the 17 holes," said Park, who had six birdies and one bogey.
Stacy Lewis, Michelle Wie, Sandra Gal, Chella Choi, Sarah Kemp, Laura Diaz, Brittany Lincicome, Jennifer Kirby and Gerina Piller were tied for sixth at four-under 67.
Johnson's round included 10 birdies and a bogey as she equalled the course record set previously by Kang Ji-Min and Laura Davies nine years ago.
Johnson birdied three of her first four holes and almost made it four straight but settled for a par on the second. She went on to post five consecutive birdies beginning at the ninth.
Johnson, who began playing golf at age nine, said getting off to a quick start Friday helped her confidence.
"I just gave myself chances all day long, and that really helps on these greens when you hit it close because if not, you're going to be hitting some bumps out there," said Johnson, who shot a 63 on this course two years ago.
Nomura's 63 was a career best score.
"All in all, my putting was on, my shot was really good and the conditions were great," Nomura said. "So everything was perfect today."
Leading scores after Friday's first round of the ShopRite LPGA Classic (USA unless noted, par-71):
62 - Jennifer Johnson
63 - Haru Nomura (JPN)
64 - Christina Kim
66 - Choi Na-Yeon (KOR), Park In-Bee (KOR)
67 - Chella Choi (KOR), Sandra Gal (GER), Stacy Lewis, Sarah Kemp (AUS), Laura Diaz, Brittany Lincicome, Jennifer Kirby (CAN), Gerina Piller, Michelle Wie
68 - Jodi Ewart Shadoff (ENG), Lee Mi-Hyang (KOR), Mina Harigae, Kang Hae-Ji (KOR), Paola Moreno (COL), Jane Park, Lydia Ko (NZL), Lindsey Wright (AUS), Caroline Westrup (SWE), Sydnee Michaels, Katy Harris, Stacy Keating