The announcement was made by Houston Athletic Director Dave Maggard at a noon press conference.
Sumlin becomes the school's 11th head coach, but the first African-American.
In making the announcement, Maggard said he found Sumlin as someone he found to be highly respected by his peers, head coaches and athletic directors nationwide.
Sumlin's success in recruiting the Houston area for both Oklahoma and Texas A&M was also noted.
"This is a great University and a great city," said Sumlin at the press conference. "This is a place that has won conference championship in recent years, and we want to continue down that path and play for a conference championship every season. This is Dave Maggard's vision, and I share the same vision.
"I bring both energy and excitement to the program, as well as an aggressive style of offense and defense. It will be a style that the players will want to play and a style that our fans will like to watch.
"What excited me (about coming to Houston) was a chance to play for a championship every year."
Sumlin replaces Art Briles, who resigned late last month for the head coaching position at Baylor.
Sumlin was at Oklahoma five seasons and was also the passing game coordinator and wide receivers coach.
He was special teams and tight ends coach for three seasons.