Al-Mughira continued his military service and lost an eye during the Battle of the Yarmuk in August 636. Caliph Umar appointed him governor of Basra, , a newly founded garrison town that served as the primary springboard for the Muslim conquest of Persia. However, his tenure there was cut short when he was dismissed following allegations of adultery.

In 642, Umar reappointed al-Mughira