Stark carded five birdies, and with her bogey-free round she shot a 66 in Evian-les-Bains, France.
The Swede is tied for third place after the first round. Japanese player Akie Iwai leads at -8.
Stark has won a major before - the 2025 US Open.
Swedes Linn Grant, Anna Nordqvist and Kajsa Arwefjäll are all tied for 20th place at two under par. Frida Kinhult, +2, is tied for 87th place.
Ingrid Lindblad is further down the list - in a share of 128th place at seven over par.
The Evian Championship is the fourth major of the season.
