Earlier today, Eyewitness Sports Director Bob Allen confirmed the Texans have agreed to terms with Leinart on a one-year deal.
Leinart was released by the Cardinals and according to the Houston Chronicle, a roster spot had been left open for Leinart on the Texans.
The 27-year-old now joins Matt Schaub and Dan Orlovsky as quarterbacks on the 53-man roster.
Leinart will be working with some of the NFL's best receiving talent, including All-Pro Andre Johnson. Leinart, who was released Saturday, also had great receivers in Arizona, led by All-Pro Larry Fitzgerald.
Leinart's financial terms for 2010 were not immediately available.
The Cardinals parted ways with the former Heisman Trophy winner days after Leinart went public with his frustration over being replaced by Cleveland castoff Derek Anderson.
Leinart complained he had outplayed Anderson and that his problems with coach Ken Whisenhunt were "probably away from football." That led to a meeting with Whisenhunt the following day. Although he was unhappy that Leinart took his issues public, Whisenhunt praised how the quarterback handled things.
"The one thing I want to make very clear is how professional Matt was about the whole situation," the coach said. "I was very impressed with his conversation with me. He thanked the organization, the ownership, for all the time and effort that they had invested in him. He felt like he had gotten better and he had learned a lot and it meant a lot to me to hear him say that."
Arizona thought it had a steal when Leinart, who led Southern California to two national championships and a third title game appearance, fell to the Cardinals at the No. 10 overall pick in 2006. He started 11 games as a rookie under then-coach Dennis Green, then the first five the following season under new coach Ken Whisenhunt. But the big left-hander went down with a broken collarbone and Kurt Warner took over.
Warner finished his career with two spectacular seasons, leading Arizona to consecutive NFC West titles, an incredible run to the Super Bowl and a 51-45 overtime victory over Green Bay in a playoff thriller last season.
Leinart threw for 3,893 yards with 14 touchdowns and 20 interceptions with Arizona.
ESPN.com contributed to this report