The Astros activated Diaz (oblique) from the 10-day injured list Tuesday, Chandler Rome of The Athletic reports.
Diaz has been sidelined since early May while dealing with a left oblique strain, but he's been cleared to return to the active roster after playing three rehab games with Triple-A Sugar Land. The 27-year-old slashed just .235/.255/.347 with two home runs across 106 plate appearances before getting hurt. Diaz should operate as the Astros' primary catcher moving forward, but Christian Vazquez will also be in the mix.