Tom Scherrer managed a 1-over 71 but held on to second place at 4-under-par 206. Greg Bruckner also shot a 71 and is one stroke further back at minus-3.
Walker came firing out of the gate, but stumbled late in his round. He notched back-to-back birdies from the second to move to minus-8 and grab a four-shot lead.
The 25-year-old settled in with eight pars in a row at Panama Golf Club. He moved five strokes clear of the field with a birdie at the par-5 12th.
It was all down hill from there for the leader. He stumbled to back-to-back bogeys from the 13th to fall back to minus-7. Walker dropped another stroke at the closing hole to lead by two heading to the final round.
'I played solid again today,' said Walker, a San Antonio resident. 'I had a couple of loose swings today that hurt me down the stretch. But I'm still happy with the way I'm playing.'
Walker will be shooting for his first Nationwide Tour win on Sunday.
'I'm still going to play aggressive tomorrow and try to make birdies,' said Walker, an All-American at Baylor. 'But at the same time you have to be smart and know when to take your pars.'
Scherrer did not do a lot during his round. He opened with a birdie at the first, but struggled to a bogey at the very next hole. He ran off eight straight pars before dropping another stroke at the par-4 11th.
'I'm happy with the position I'm in,' Scherrer said. 'I left a lot of shots out there today, but the course is playing so difficult. I've been in this position before. But you can have all the experience in the world but you still have to execute.'
Scherrer parred out his final seven holes for second place.
Paul Gow posted a one-under 69 and shares fourth place with Jason Caron (70) at 2-under-par 208. Ryan Armour and Jeff Mixon each carded 2-under rounds of 68 to join Bryant Odom (71) at 1-under-par 209. Jess Daley and Chris Zambri are one stroke further back at even par.
Curt Byrum and Steve Ford tied for best round of the day as they both shot 3-under 67. They are tied at 1-over-par 211 with Jeff Quinney, Chris Sessler, Jason Schultz and Brian McCann.