In recent years, the number of randomized controlled trials using cohorts and routinely collected data (e.g., electronic health records, administrative databases, and health registries) has increased. Such trials can ease the challenges of conducting research and save cost and time. Accordingly, to standardize such trials and increase the transparency and completeness of research reports, an international panel of experts developed the CONSORT-ROUTINE (2021) reporting guideline. The reporting guideline was published in 2021 in the BMJ. To help understand and formally apply the reporting guideline and improve the overall quality of this type of study, the present paper introduced and interpreted the development process and reporting checklist of the CONSORT-ROUTINE.