Intervention research on adults with autism spectrum disorder (ASD) is sparse. Many adults with ASD experience impaired emotion regulation (ER), which is thought to contribute to higher rates of psychiatric comorbidities among adults with ASD and indirect effects upon adaptive functioning, interpersonal relationships, and vocational status. The purpose of this study was to investigate feasibility and initial efficacy of an adapted mindfulness-based individual therapy targeting ER difficulties for adults with ASD. There is evidence for feasibility based on acceptable treatment fidelity and participant satisfaction ratings. Of nine participants, seven demonstrated improvement in at least one of the following domains; impulse control, access to ER strategies, and emotional acceptance. Further research is recommended, including additional timepoints and a clinical cutoff-derived sample.