Kubiak was carted off the field and taken to a hospital at halftime of Houston's game Sunday. It was determined he suffered a minor stroke. He is expected to make a full recovery and was released from the hospital Tuesday.
However, it was unclear when Kubiak would be able to return to coaching, leading the Texans to turn to Phillips.
Phillips filled in a head coach the second half of Sunday's game. It is his third stint as an interim head coach, having taken those roles in New Orleans in 1985 and Atlanta in 2003.
He was the head coach at Denver from 1993-94, Buffalo from 1998-2000 and Dallas from 2001-10. He has an overall coaching record of 82-59.