Otto was called up from Triple-A Round Rock ahead of his start Friday against the Astros.
The Rangers announced earlier in the week that Otto would start in place of Spencer Howard (undisclosed) and now the club has officially made room on the 26-man roster by placing Howard on the COVID-19 injured list. Otto will be making his major-league debut after posting a 3.20 ERA while logging 95.2 innings between Double-A and Triple-A this season.