Anxiety affects one in four New Zealanders at some time in their life and current treatments are unaffordable. Heightened neural arousal influences the extent of anxiety. There is growing research to support sensory modulation as an intervention to regulate emotional and physiological arousal, however further evidence is needed to support this approach with people experiencing severe mental illness. This one group prospective quasi-experimental design study evaluated the effectiveness of a brief sensory modulation intervention in reducing anxiety for people accessing mental health services. It consisted of three phases; baseline, intervention and follow-up with data collected throughout. The stability of the data collected during the baseline phase enabled the intervention group to act as their own controls. The data were analysed to determine whether the participants experienced changes in self-reported anxiety and quality of life. Participants showed a significant reduction in anxiety, measured using the Beck Anxiety Index, and this reduction continued at three months follow up. There was significant support for effectiveness of the intervention in increasing participation, as measured by the The World Health Organization Disability Assessment Schedule. However, the results of The World Health Organization Quality of Life measures did not support the hypothesis that the intervention would improve overall quality of life. Overall, the results indicate that a three-session sensory modulation intervention could provide a limited cost approach for reducing anxiety and increasing participation in people accessing community mental health services.