The former Burnside High School student shot a one-under-par 70 on the Cypress Creek course in Houston, Texas, to sit just three shots off the lead after 18 holes.
While Garvey admitted there were some nerves heading into her first major, her play didn't reflect that as she started her round in fine form with a birdie on her first hole.
"That was a good way to start. But it probably got me a bit more nervous to be fair. I said to my caddie 'whoa, I might actually be leading the US Open' because I was one of the first ones off," Garvey said.
"I was really smart with my targets out there today. It's playing tough; the wind was swirling and it was really hot so the greens were really firm. I'm happy with the way I grinded it out and got in under par.
"I just had so much fun out there. After eight months off I thought I'd be rustier than a nice wee 70, one-under.
"I said to my caddie when we were walking off the green, I actually thought to myself this morning, I have the game to win this thing, and then coming down 18, which was my ninth hole today, it was nice to see 'Garvey' up on the leaderboard, so I'm just enjoying it and enjoying being in the position that I'm in because I've worked hard and I deserve to be here, so just go out there and do the same thing tomorrow."
After ending the opening round in a tie for 12th, she will look to push on when she plays the Jackrabbit course tomorrow.
Fellow Kiwi and former World No 1 Lydia Ko wasn't much further off the pace in her opening round, finishing with an even 71 on the Jackrabbit course to sit in a tie for 24th.
Ko had a rather erratic round, with three birdies, one eagle, three bogies and one double bogey on her score card.
American Amy Olson sits atop the standings after the opening round of play on four-under, with Japan's Hinako Shibuno, Thailand's Moriya Jutanugarn, South Korean A Lim Kim, and Filipino Yuka Saso tied for second on three-under.
