Background: The growing interest in co-creation for public health innovation highlights the need for systematic approaches to stakeholder engagement. Despite its potential, co-creation faces substantial challenges, including unresolved power dynamics, poor reporting of methods and the absence of a universally agreed-upon definition. Current research reveals substantial fragmentation in co-creation literature, with limited guidance on method selection and principle alignment. This study addresses these gaps by developing a framework for systematically evaluating method alignment with key co-creation principles, offering a structured approach to fostering more effective and adaptive collaborative processes. Methods: Using a structured review approach based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, image-based models representing co-creation principles from academic and non-academic sources were identified and assessed. A framework was created through an iterative development process. The framework was subsequently validated by 12 geographically diverse co-creation researchers using a closed card sort method, ensuring its robustness and applicability across different research contexts. Results: The Co-Creation Rainbow Framework was developed by integrating key features from 20 included models, creating an individual-to-collective continuum with five sections (informing, understanding, stimulating, collaborating and collective decision-making), and three themes (engage, participate and empower). Successfully mapping 416 methods to the framework demonstrated its robust capability to differentiate and categorize co-creation methods, and reveaed nuanced variations in methodological strategies used by researchers and practitioners across different contexts. Conclusions: The Co-Creation Rainbow Framework addresses the disconnect between theoretical and practical co-creation approaches through operationalising co-creation principles. By challenging traditional linear models and acknowledging the diversity of co-creation methods, the framework provides a nuanced and adaptable tool for systematically evaluating method alignment. The framework offers researchers and practitioners a robust tool for meaningful collaborative innovation, ultimately opening new pathways for collective problem-solving and knowledge generation.