Romo completed 19-of-31 passes for 279 yards as the Cowboys (4-4) bounced back from a humbling 34-7 defeat at the hands of NFC East rival Philadelphia last week.
DeMarco Murray ran for 139 yards on 22 carries in the Cowboys' victory.
The Seahawks (2-6) struggled under Tarvaris Jackson, who went 17-for-30 through the air for 221 yards and three second-half pick-offs.
Marshawn Lynch rushed for 135 yards and a score on 23 carries but it wasn't enough to prevent Seattle's third straight loss, during which the Seahawks have scored only 28 points.
Rosie O'Donnell unveils nearly 50-pound weight loss
Iranian woman stops the execution of son's killer