The overturned big rig blocked all mainlanes of I-69 south at the SH-288 split.
The accident caused miles of backups for Houston drivers during the morning commute.
The freeway officially reopened around 8:45 a.m.
Video showed the 18-wheeler on its side, with two heavy wreckers at the scene. It appeared the 18-wheeler lost its load.
It's unclear what exactly led up to the crash.