The Rangers selected Speas' contract from Triple-A Round Rock on Wednesday.
Speas will join the major-league roster for the first time in his career after being selected in the second round of the 2016 MLB Draft. The right-hander has produced a 2.35 ERA and 1.11 WHIP with 12 strikeouts over 7.2 innings in five appearances with Round Rock this season. In order to make a spot on the 40-man roster for Speas, left-hander Taylor Hearn was designated for assignment Wednesday.