Romo suffered a back contusion during the Cowboys' 20-17 overtime loss to the Washington Redskins that forced him from the field in the third quarter.
The 34-year-old underwent a CT scan, though the results have not been disclosed.
Romo also sat out practice on Thursday but Garrett believes the QB is a chance to face National Football Conference (NFC) rivals the Cardinals (6-1) at AT&T Stadium.
"Sounds like he's feeling better," Garrett said.
"Yeah but just talking to him, it sounds like he's feeling better.
"And typically that happens the further away you are from an injury, hopefully the better it gets. You get the blood flowing through your body.
"So hopefully he's able to do something today and we can build on that."
The Cowboys have won six of their eight games this season to sit top of the NFC East.