Given the substantial investment in the development of mental health mobile applications (apps), information about penetration in the patient populations of interest is critical. This study describes the proportion of veterans who are knowledgeable of and utilize the Department of Veteran Affairs (VA) and Department of Defense (DoD) mental health apps. A cross-sectional survey of 140 veterans was conducted in primary care and outpatient mental health clinics at a large VA facility. Ninety-one percent of veterans (n = 127) reported smartphone ownership. Of these, 42.5% and 20.4% had heard of and used at least one of the 22 VA/DoD mental health apps, respectively. When veterans were asked to pick the individual VA/DoD apps they had previously used from a list, the proportion of participants who reported prior use ranged from 0% (Moving Forward) to 6.5% (Mindfulness Coach). Treatment for psychiatric problems relevant to the apps did not predict veteran knowledge/use of the VA/DoD apps. Rates of app use remained low among veterans reporting symptoms/diagnoses apps were designed to address (e.g., 7.5% of veterans who reported posttraumatic stress disorder (PTSD) had used PTSD Coach). The most common barrier to app use (endorsed by 65.7% of participants) was awareness of the apps. Expansion of existing VA/DoD efforts to educate patients and providers treating relevant conditions is indicated. Evaluation of evidence-based mobile health support specialists in clinical settings may also be indicated. This study provides critical information to guide future dissemination efforts and to help evaluate the impact of investments to date. Impact StatementAmong treatment-engaged military veterans who owned a smartphone, only 43% had heard of and 20% had used any of the Department of Veterans Affairs or Department of Defense mental health mobile applications (apps). Public sector psychologists in a variety of settings may benefit from research on the rates of mental health app penetration in patient populations of interest to explore the need for strategic dissemination efforts.