There is considerable interest in collaborating with social media influencers to promote health messages, but little evidence demonstrating how this might be done in organizations with few resources or experience. We tested the feasibility and cost of partnering with social media nano- and micro-influencers to promote colorectal cancer (CRC) screening messages. We identified 16 US influencers through an online influencer marketing campaign platform. To test if influencers would create theory-consistent content, we provided them with recommended CRC screening information and guidelines for including one of four message strategies (threat, efficacy, threat and efficacy, information only). Influencers created and posted one video promoting CRC screening on their Instagram Reels and Stories, June–July, 2025. Engagement metrics were collected 1 month after posting. The videos were viewed 89 764 times (M = 5610, SD = 5545), and cost $0.13 per view. They did not elicit resistance; comments were 96% positive, 4% neutral, 0% negative, and engagement rates were high (mean = 7.9%). Influencers were largely able to follow written guidance for including theory-based content in their posts. In light of the rise in social media use, including among middle-aged and older adults, partnerships between public health organizations and social media influencers could expand health message reach.