Liselotte Neumann also posted a 64 on Saturday and is tied for second place with last week's Office Depot Championship winner Hee-Won Han, who carded a 66 in round three. The pair is knotted at minus-11.
Sherri Turner (66), Jennifer Rosales (67) and Sherri Steinhauer (69) share fourth place at 9-under-par 204.
Perrot began the third round two shots out of the lead, but flew out of the gate on Saturday. She parred her first two holes, then reeled off four birdies in a row from the third, all from inside 6 feet.
She drained a 12-foot birdie putt at the ninth to reach 12 under par for the championship. Perrot three-putted the 13th green for her only bogey of the round, but the 21-year-old distanced herself from the field later on the back nine.
At the par-3 14th, Perrot ran home an 8-footer for birdie. She made it two in a row with a birdie at the 15th. Perrot missed the green with his 5-iron second shot, but chipped to 4 feet and converted the birdie putt to get to 13 under par.
Perrot split the fairway with her drive at the last, then hit a 6-iron to 10 feet. She drained that birdie putt to move three ahead.
'Today I felt pretty comfortable in my game,' said Perrot. 'I think the whole day I played pretty solid. I just made one bogey. I am making one shot at a time.'
Perrot is an LPGA Tour rookie and in search of her first victory. She won twice on the Futures Tour in 2004, but is surprising cool considering she might be one day away from her first LPGA Tour title.
'I'm not pushing nothing,' said Perrot. 'My mental set is to come here and play my game and have fun, that's important. I have more important things to me here. I think sometimes we take too seriously what we do. Sport is made to have fun.'
Neumann was 2 under par through 10 holes, then caught fire. She birdied her next six holes, including tap-ins at the 13th and 15th holes. Neumann got to 12 under par for the championship at 16 when her 7-iron landed 12 feet from the hole.
Trouble loomed for Neumann at No. 17. She hit another solid 7-iron to 15 feet, but missed her birdie try by almost 3 feet. Neumann failed to put the ball into the cup from there, but would not let a late bogey ruin an otherwise spectacular round.
'A couple of mistakes, a couple of missed short putts, but overall probably one of my best ball striking days, I think, in a long time,' said Neumann. 'I played extremely good today.'
Han was also 2 under at the turn, but a stretch in the middle on her second nine ascended her up the leaderboard. She tapped in a 2-footer for birdie at 13, then came back and birdied No. 14. Han two-putted from 45 feet at the par-5 15th and got within three of the lead.
'I feel pretty good from last week,' said Han, who waited until Monday to claim last week's Longs Drugs title. 'I hope to play well tomorrow.'
Hall of Famers Juli Inkster (67) and Beth Daniel (70), Lindsey Wright (70), and overnight leader Dawn Coe-Jones (72) are knotted in seventh place at 8-under-par 204.
Defending champion Christina Kim struggled to a 3-over 74 on Saturday and is part of a group tied for 30th place at minus-3.