In 2018, Mycoplasma ovipneumoniae was detected in free-ranging caribou (Rangifer tarandus grantii) and Dall's sheep (Ovis dalli dalli) in Alaska, US. Evaluation of additional nasal swabs and archived tissues for M. ovipneumoniae suggested that this bacterium was widespread geographically and temporally in populations of both species. Multilocus sequence typing of four loci identified a single, novel, apparently stable strain type of M. ovipneumoniae in 11 Dall's sheep and 15 caribou in multiple populations across Alaska sampled over a period of 15 yr (2004–19). This strain type differs from those detected to date from wild or domestic sheep (Ovis aries) or goats (Capra aegagrus hircus) tested in Alaska or the lower 48 states. Although the population health implications of this strain are unknown, it has not been associated with population-wide mortality events. The presence of this strain does not decrease the potential risk from the introduction of a pathogenic M. ovipneumoniae strain associated with severe disease in other wildlife populations; therefore, continued monitoring for signs of disease and additional strains is important.