Raiders head coach Jon Gruden confirmed the trade, saying the team wants to give playing time to other young cornerbacks on the roster.
The teams didn't disclose the terms of the deal. League sources told NFL Media the Texans sent a 2020 third-round draft pick to the Raiders for the defensive back.
"It was a tough decision, obviously, and we certainly wish Gareon the best," Gruden told reporters Monday. "Good young player. We do have some young corners that we drafted -- Trayvon Mullen, we have Isaiah Johnson coming back soon [from injured reserve], Keisean Nixon, Nevin Lawson is coming back.
"We want to look at some younger players and wish Gareon the best. Thank him for his contribution."
The Texans have been thin in their secondary, as starting cornerbacks Johnathan Joseph and Bradley Roby each have missed time with injuries. Roby didn't play in Houston's loss to the Indianapolis Colts on Sunday and isn't expected to suit up next week.
Through six games this season, Conley has 23 total tackles, one interception and two passes defensed.
The Texans and Raiders will play on Sunday.