Allen signed a minor-league contract with the Rockies on Friday.
Allen reported to Triple-A Albuquerque and made his debut for the affiliate Sunday, when he struck out two and allowed three earned runs on four hits and one walk over three innings. The Rockies mark the third organization of the season for Allen, who began the campaign as a member of the Guardians before he was waived and claimed by the Orioles, who released him earlier this month. For the season, Allen owns an 8.56 ERA in 27.1 innings at the Triple-A level.