BackgroundCanada’s 24-Hour Movement Guidelines for Adults have shifted the focus from considering movement behaviours (i.e., physical activity, sedentary behaviour, and sleep) separately to a 24-h paradigm, which considers how they are integrated. Accordingly, primary care providers (PCPs) have the opportunity to improve their practice to promote all movement behaviours cohesively. However, PCPs have faced barriers to discussing physical activity alone (e.g., time, competing priorities, inadequate training), leading to low frequency of physical activity discussions. Consequently, discussing three movement behaviours may seem challenging. Tools to facilitate primary care discussions about physical activity have been developed and used; however, few have undergone usability testing and none have integrated all movement behaviours. Following a synthesis of physical activity, sedentary behaviour, and sleep tools for PCPs, we developed the Whole Day Matters Tool and User Guide that incorporate all movement behaviours. The present study aimed to explore PCPs’ perceptions on the usability, acceptability, and future implementation of the Whole Day Matters Tool and User Guide to improve their relevancy among PCPs.MethodsTwenty-six PCPs were observed and audio–video recorded while using the Tool and User Guide in a think-aloud procedure, then in a near-live encounter with a mock service-user. A debriefing interview using a guide informed by Normalization Process Theory followed. Recordings were transcribed verbatim and analysed using content analysis and a critical friend to enhance rigour.ResultsPCPs valued aspects of the Tool and User Guide including their structure, user-friendliness, visual appeal, and multi-behaviour focus and suggested modifications to improve usability and acceptability. Findings are further discussed in the context of Normalization Process Theory and previous literature.ConclusionsThe Tool and User Guide were revised, including adding plain language, reordering and renaming sections, reducing text, and clarifying instructions. Results also informed the addition of a Preamble and a Handout for adults accessing care (i.e., patients/clients/service-users) to explain the evidence underpinning the 24-Hour Movement Guidelines for Adults and support a person-centered approach. These four resources (i.e., Tool, User Guide, Preamble, Handout) have since undergone a consensus building process to arrive at their final versions before being disseminated into primary care practice.