Commercial companies invest in sport and arts sponsorship to align their brand with highly engaged spectators. Competing for spectator attention are government and non-government organizations promoting healthy lifestyles. This study investigated spectator engagement on the effectiveness of health messages promoted at sponsored events. Surveys from 2165 adults attending 28 sponsored events collected data on event engagement, health message awareness, behavioral intention, and perceptions of sponsor fit and sincerity. Spectators who were more highly engaged in the event showed significantly greater levels of awareness and acceptance of the health message (all P < 0.01). Path analysis showed that product and event interest were significantly related to both fit and sincerity, and perceived sponsorship fit was significantly associated with greater behavioral intention (all P < 0.01). Product, category and event interest, fit and sincerity were significantly greater for positive advocacy messages than neutral or negative advocacy messages (all P < 0.05). Health message sponsorship is assisted by spectator engagement and perceived fit of sponsored health messages. There exists greater potential to actively leverage spectator engagement to build or reinforce the perceived fit and sincerity of health messages to strengthen existing awareness and behavioral intention.