Objective Fibromyalgia is a functional pain disorder in which patients suffer from widespread pain and poor quality of life. Fibromyalgia pain and its impact on quality of life are not effectively managed with current therapeutics. Previously, in a preclinical rat study, we demonstrated that exposure to green light-emitting diodes (GLED) for 8 hours/day for 5 days resulted in antinociception and reversal of thermal and mechanical hypersensitivity associated with models of injury-related pain. Given the safety of GLED and the ease of its use, our objective is to administer GLED as a potential therapy to patients with fibromyalgia. Design One-way crossover clinical trial. Setting United States. Method We enrolled 21 adult patients with fibromyalgia recruited from the University of Arizona chronic pain clinic who were initially exposed to white light-emitting diodes and then were crossed over to GLED for 1 to 2 hours daily for 10 weeks. Data were collected by using paper surveys. Results When patients were exposed to GLED, but not white light-emitting diodes, they reported a significant reduction in average pain intensity on the 10-point numeric pain scale. Secondary outcomes were assessed by using the EQ-5D-5L survey, Short-Form McGill Pain Questionnaire, and Fibromyalgia Impact Questionnaire and were also significantly improved in patients exposed to GLED. GLED therapy was not associated with any measured side effects in these patients. Conclusion Although the mechanism by which GLED elicits pain reduction is currently being studied, these results supporting its efficacy and safety merit a larger clinical trial.