Veterans with post-traumatic stress disorder (PTSD) face significant barriers that make it less likely for them to pursue treatment. A randomized controlled non-inferiority trial was used to determine if providing psychotherapy for PTSD via videoconference (VC) is as effective as in-person (IP) psychotherapy. All eligible veterans (  = 207) received cognitive processing therapy (CPT) to treat PTSD symptoms in one of the two treatment modalities. Participant symptoms were collected at baseline, post-treatment, and six months after treatment completion. The primary outcome measure, the Clinician-Administered PTSD Scale (CAPS), was used to assess PTSD diagnosis and symptom severity. Secondary outcomes included two self-report measures of symptom severity, the Post-traumatic Stress Disorder Checklist - Specific (PCL-S) for PTSD and the Patient Health Questionnaire - 9 (PHQ-9) for depressive symptoms. A linear mixed-effects model was used to assess non-inferiority for participants who completed treatment (completers) and those who were randomized to treatment (intention-to-treat (ITT)). Both completer and ITT analyses showed that improvement in CAPS scores in the VC condition was non-inferior to that in the IP condition at six-month follow-up, but VC was inferior to IP for improvement in CAPS at post-treatment. Non-inferiority was supported by completer analyses for PCL-S and PHQ-9 in both post-treatment change and six-month follow-up change, and the ITT analysis supported the significant non-inferiority for PCL at post-treatment change. These findings generally suggest that CPT delivered via VC can be as effective as IP for reducing the severity of PTSD symptoms.