Previous researchers have found that 10-form Tai chi yields symptomatic benefit in patients with fibromyalgia (FM). The purpose of this study was to further investigate earlier findings and add a focus on functional mobility. We conducted a parallel-group randomized controlled trial FM-modified 8-form Yang-style Tai chi program compared to an education control. Participants met in small groups twice weekly for 90 min over 12 weeks. The primary endpoint was symptom reduction and improvement in self-report physical function, as measured by the Fibromyalgia Impact Questionnaire (FIQ), from baseline to 12 weeks. Secondary endpoints included pain severity and interference (Brief Pain Inventory (BPI), sleep (Pittsburg sleep Inventory), self-efficacy, and functional mobility. Of the 101 randomly assigned subjects (mean age 54 years, 93 % female), those in the Tai chi condition compared with the education condition demonstrated clinically and statistically significant improvements in FIQ scores (16.5 vs. 3.1, p = 0.0002), BPI pain severity (1.2 vs. 0.4, p = 0.0008), BPI pain interference (2.1 vs. 0.6, p = 0.0000), sleep (2.0 vs. -0.03, p = 0.0003), and self-efficacy for pain control (9.2 vs. -1.5, p = 0.0001). Functional mobility variables including timed get up and go (-.9 vs. -.3, p = 0.0001), static balance (7.5 vs. -0.3, p 0.0001), and dynamic balance (1.6 vs. 0.3, p = 0.0001) were significantly improved with Tai chi compared with education control. No adverse events were noted. Twelve weeks of Tai chi, practice twice weekly, provided worthwhile improvement in common FM symptoms including pain and physical function including mobility. Tai chi appears to be a safe and an acceptable exercise modality that may be useful as adjunctive therapy in the management of FM patients. (ClinicalTrials.gov Identifier, NCT01311427).