Hayne was then given a crack at running back to open the second half and after a few short gains burst free with a 34-yard run on his fourth carry down the left sideline.
His eight carries in total netted a game high 54 yards for runners, sparking commentators to call him "the biggest story in pro football so far this season."
He even played on special team's defence, limiting a Cowboys return by getting the first touch on a Dallas returner.
When asked of Hayne's returns, head coach Jim Tomsula in trying to limit the pressure on Hayne, said: "Second game of the pre-season, he's just got to keep working."
Hayne was asked in an on-field interview if there was anything he didn't do.
"I don't play quarterback," he joked.
"No, I'm just grateful for the opportunity, wherever I get the opportunity on the field I'm there.
"I am still getting used to lowering my pads and running off the right blocks. I am just trying my best every week and studying and really enjoying the process. I am over here having a crack and doing my best.
"I'm still a long way off from where I want to be. I want to go into games confident that everything I do, I'm comfortable with. People might be surprised in how I'm going but I've got confidence in my ability."
Hayne's efforts continued to impress the 49ers' star quarterback Colin Kaepernick.
"He's constantly improving and building a strong resume in a short time," said Kaepernick.
"He's very calm and confident in what he's doing, and it shows."
Continuing his quest to make the 49ers fulltime roster, Hayne had previously run for 63 yards on five carries at running back and compiled 120 all-purpose yards in week one's 23-10 loss to the Houston Texans.
The highlight was a 53-yard carry in the second quarter that nearly wound up in the end zone.
The 49ers travel to Denver next Saturday.
