Lohse was set to pitch Saturday night at home against Minnesota.
Lohse was 2-5 with a 5.06 ERA in 10 starts in the minors for Round Rock. The AL West-leading Rangers have had several injuries in their rotation this season.
Lohse, 37, is 147-141 in 15 big league seasons. A right-hander, he went 5-13 for Milwaukee last year. He also has pitched for Minnesota, Cincinnati, Philadelphia and St. Louis.
To make room for Lohse on the roster, Texas optioned right-hander Nick Martinez to Round Rock late Friday.