Background/Objectives: Self-management for adults living with intestinal stomas secondary to colorectal cancer encompasses technical ostomy care, physical symptom control, psychological adjustment, and social participation, creating demand for standardised assessment instruments to identify unmet rehabilitation needs. Definitions of generic self-care and stoma-specific self-management remain inconsistent across published literature, and psychometric indicators are incompletely reported across available measurement instruments. This review includes both stoma-specific instruments and generic self-care scales that have been validated or widely applied specifically in colorectal cancer ostomy cohorts. Following JBI scoping review methodology, this work systematically maps all published self-management assessment instruments developed for adults with intestinal stomas secondary to colorectal cancer, summarises their core measurement domains and documented psychometric properties, and identifies prevailing gaps in scale development and validation research. Methods: This scoping review was conducted in accordance with Joanna Briggs Institute methodological guidance and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) reporting checklist. Ten electronic databases were searched from inception to 31 December 2025, with supplementary manual screening of reference lists. Eligible sources were peer-reviewed English or Chinese articles focusing exclusively on adults with colorectal cancer–related intestinal stomas. Two independent researchers completed title/abstract and full-text screening, followed by data extraction using a piloted standardised form. Consistent with descriptive scoping review design, no formal methodological quality evaluation or risk-of-bias assessment was performed. Results: Thirty-two studies involving 12 self-management assessment instruments were finally included. All tools documented Cronbach’s α coefficients ranging from 0.805 to 0.977. Content validity indicators were documented for eight instruments, whereas construct validity verified via factor analysis or structural equation modelling was only available for three tools. Criterion-related validity, cross-cultural validity and responsiveness were scarcely reported across most instruments. Only three instruments were fully developed based on complete and clearly articulated theoretical frameworks. Four consistent core measurement domains were identified across scales: stoma technical care, symptom and complication management, psychological adaptation, and family-social interaction. Conclusions: Although internal consistency metrics are universally reported, comprehensive multi-faceted validity testing and responsiveness evaluation are largely absent from existing published evidence. Cross-cultural measurement invariance between original and locally adapted versions (such as the ESCA and its Chinese revised forms) has rarely been examined. Future research priorities include rigorous cross-cultural adaptation following International Society for Pharmacoeconomics and Outcomes Research (ISPOR) and Consensus-based Standards for the selection of health Measurement INstruments (COSMIN) protocols, full psychometric verification of currently available instruments, and development of brief validated short forms for clinical screening. New instrument development should only be initiated if existing tools fail to capture core rehabilitation priorities identified by patients, caregivers, and clinical staff. No responsiveness metrics were identified across the 32 included colorectal cancer-specific clinical studies. The absence of relevant evidence in this literature pool does not prove that these instruments cannot detect longitudinal changes; formal responsiveness testing is required before applying these tools for long-term outcome monitoring.