Grace Park is two shots behind Redman at 5-under 67. Rosie Jones, Christie Kerr and Laura Diaz are each at minus-4, while Paula Marti, Mi Hyun Kim and Se Ri Pak are 3-under.
Redman, who blew a 5-up lead with five holes to play against Suzann Pettersen at the Solheim Cup two weeks ago, also tied the tournament record for lowest first-round score. Her two-putt birdie on the final hole gave her the 65.
'I felt like I played really good golf there (at the Solheim Cup),' said Redman. 'I've been playing really well since July. That's what I want to continue, playing really consistent and hitting a lot of greens.'
Redman began her birdie run at the par-4 fourth. Her 7-iron landed within five feet of the cup, before she struck again with an 18-foot birdie at the par-3 sixth. Redman stuck a sand wedge inside three feet for birdie at the seventh to make it two in a row.
Her hot play continued with birdies at 10, 11, and 13. After sinking short putts at 10 and 11, Redman chipped in at the 13th for the birdie. She closed her round by two-putting from 50 feet on the par-5 18th.
'I had a terrible lie on 18,' Redman said. 'You really couldn't tell, but I had a downhill, right to left lie. I've been putting a lot better recently, I think that has a lot to do with how well I played.'
Sorenstam, the top-ranked player in the world, caught fire on the back nine with three birdies and a hole-in-one. It was her bogey on the final hole that kept her from tying Redman for the lead.
'I think this is my sixth hole-in-one as a pro,' said Sorenstam. 'I'm playing well right now and momentum is on my side. It can't get any better.'
Sorenstam hit a wedge to six feet on the 10th and knocked a pitching wedge inside six feet at the 11th. She then chipped within three feet for birdie at the par-5 16th before holing a 5-iron at the 185-yard par-3 17th. Sorenstam followed the ace with a bogey at the last after a poor second shot.
'I wanted a pitching wedge or 9-iron in,' Sorenstam said. 'I tried to cut a 7-wood, but it went way right. That was a bad mistake on my side.'
Jones, who collected the winning point at the Solheim Cup, started her day with a bogey at the first but responded with three birdies on the front side to make the turn at minus-2. She added two birdies on the back nine to get to 4-under.
Lorie Kane and Juli Inkster are at 2-under. Inkster survived a double-bogey seven on the par-5 16th, after losing two balls in a hazard.
Defending champion Dorothy Delasin carded an even-par 72 to finish tied for 12th alongside Rachel Teske.
Full-field scores from the Samsung World Championship