The two Houston quarterbacks have battled throughout training camp to win the backup position behind Matt Schaub.
Keenum got the start and completed 9-of-13 for 128 yards. Yates went 8-of-11 for 109 yards.
Houston played two rookie running backs and they combined for 186 yards. Cierre Wood had 107 yards and Dennis Johnson added 79 despite fumbling three times, only one of which was lost.
Alex Tanney completed 17-of-31 passes for 177 yards, but failed to get the Cowboys in the end zone.
The Texans completed the preseason at 3-1 while Dallas went 2-3.
The Cowboys will be at home on the evening of Sept. 8 to open the regular season against the division rival New York Giants. Houston, having produced its first two playoff appearances during the last two seasons, will visit San Diego in one of the two Monday night contests played next week.