Although exercise is often recommended for managing osteoarthritis (OA), limited evidence-based exercise options are available for older adults with OA. This study compared the effects of Hatha yoga (HY) and aerobic/strengthening exercises (ASE) on knee OA. Randomized controlled trial with three arms design was used: HY, ASE, and education control. Both HY and ASE groups involved 8 weekly 45-min group classes with 2-4 days/week home practice sessions. Control group received OA education brochures and weekly phone calls from study staff. Standardized instruments were used to measure OA symptoms, physical function, mood, spiritual health, fear of falling, and quality of life at baseline, 4 and 8 weeks. HY/ASE adherences were assessed weekly using class attendance records and home practice video recordings. Primary analysis of the difference in the change from baseline was based on intent-to-treat and adjusted for baseline values. Eight-three adults with symptomatic knee OA completed the study (84% female; mean age 71.6 +/- 8.0 years; mean BMI 29.0 +/- 7.0 kg/m(2)). Retention rate was 82%. Compared to the ASE group at 8 weeks, participants in the HY group had a significant improvement from baseline in perception of OA symptoms (-9.6 [95% CI -15.3, -4]; p = .001), anxiety (-1.4 [95% CI -2.7, -0]; p = .04), and fear of falling (-4.6 [-7.5, -1.7]; p = .002). There were no differences in class/home practice adherence between HY and ASE. Three non-serious adverse events were reported from the ASE group. Both HY and ASE improved symptoms and function but HY may have superior benefits for older adults with knee OA. Trial registration The full trial protocol is available at clinicaltrials.gov (NCT02525341).