Coach Gary Kubiak said Monday that Cushing will take over the position for DeMeco Ryans, who's out for the season after rupturing his left Achilles' tendon in the Texans' 35-31 win over Kansas City on Oct. 17.
Cushing has been starting at outside linebacker since the Texans drafted him in 2009.
"We thought that was the best thing for our team," Kubiak said. "We want him to lead the defense, take over the defense."
Ryans, who's played in the last two Pro Bowls, is a huge loss to Houston's already poor defense.
Cushing was NFL Defensive Rookie of the Year last season after making 133 tackles, including four sacks, and intercepting four passes. He was a first-round pick out of Southern Cal, where he played outside linebacker.
The Texans also released defensive tackle Frank Okam, a former Texas Longhorn.