Objective: To co-design and test the acceptability of a peer-led web-based resource (PLWR) for cancer carers to provide practical and emotional advice on common issues. Methods: A six-step co-design model informed PLWR development. Content was developed through three cancer carer workshops and monthly meetings with an expert advisory team (n = 12). User-testing was conducted via web-based survey and telephone interview. Descriptive statistics and thematic analysis were utilised. Google analytics explored site visits, commonly used components, and time spent using the PLWR. Results: The PLWR was developed to deliver cancer carer information tailored to each stage of the illness trajectory regardless of cancer type, in the form of videoed personal experiences. From November to May 2018, there were 2789 unique visits to the PLWR with 743 returners. The majority of time was spent on the full unclipped peer stories (414 views), and diagnosis-specific information (159 views), with less time spent on bereavement, cancer treatment, or self-care (120 views each). Fifty-five individuals completed the resource evaluation, with 10 participating in telephone interviews. Fifty-four carers rated the resource as excellent, useful, and easy to use. The web-based videos were regarded as convenient as and less burdensome than written information. The resource provided relevant information, potentially reducing isolation and uncertainty. Conclusion: The content and design of the PLWR appear acceptable to cancer carers. The co-design model is an effective way to develop appropriate information for service users and could be utilised as a framework for development of other interventions in a variety of disease groups.