Amid the picture-postcard setting of France's Evian Resort Golf Club, Park hit four bogeys and three birdies to leave her six shots adrift of the first-round leaders, Lexi Thompson and South Korea's My Hyang Lee.
The 27-year-old Park has won six of the last 14 majors -- most recently the British Open at Turnberry in August
-- and has been so dominant that few would have bet against taking the fifth and final major of the Ladies Professional Golf Association (LPGA) season.
Park won the tournament back in 2012, a year before it was elevated to "major" status
but may struggle to repeat the feat after making a stuttering start hitting a one-over par round of 72 to leave her in a tie for 40th.
America's Thompson, on the other hand, had a faultless round, racing to five-under after six holes, including an eagle at the par five 13th — her 4th hole after teeing off at the 10th — before parring the final 12 holes.
"Overall it was a very steady day — I had a good stretch on the first nine with a few birdies and an eagle so that always helps out with the scorecard," Thompson told CNN's The Clubhouse after her round.
"It was great conditions out there, I couldn't have asked for anything better."
Lee joined Thompson with the final shot of her round, holing out for a birdie at the ninth (her 18th hole), putting the Korean on course for her best finish at the championship -- her previous best is tied 19th in 2013.
One shot further back are a group of six players which includes China's Shanshan Feng -- winner of the 2012 PGA Championship -- and America's Beth Allen.
New Zealand teenager Lydia Ko, who finished runner-up to Norway's Suzann Pettersen two years ago, is sitting on two-under par after 18 holes.
Michelle Wie will do well to improve on her best finish of 37th after slumping to a four-over par 75 on day one.
The American, who broke her major duck last year when she won the U.S. Women's Open, is currently in a tie for 80th.