Objectives: This study identifies facilitators and challenges in the co-creation of digital health interventions for public health. Study design: An exploratory multiple case study design was used to analyse three co-created digital health interventions. Methods: Data were collected for three digital health interventions via expert interviews (n = 11), open-ended survey responses (n = 10), and project descriptions. Qualitative content analysis was conducted to identify common themes across cases. Results: Key facilitators included leveraging co-creator expertise, maintaining regular co-creator exchanges, ensuring an adaptive development process, carrying out a needs analysis and adopting a feasible design. Key challenges included resource constraints, difficult co-creator relationships, poor planning of co-creation, difficulties in recruiting and acknowledging co-creators, distributing workload fairly, and unclear expectations and skills/knowledge gap amongst co-creators. Conclusions: Findings suggest that while the facilitators and challenges of digital health interventions reported here reflect previous literature relating to non-digital health interventions, digital settings present unique challenges, including effective integration of co-creators across iteration cycles and enabling collaboration across a large array of disciplines. Understanding facilitators and challenges in digital health intervention co-creation may help teams plan how to effectively include all relevant co-creators in the process. Future research should further explore how co-creation impacts digital health intervention adoption, user engagement, and long-term effectiveness.