Background:
     
     The global push to scale up telemedicine services is challenged by complex, multilevel, multifaceted implementation and a lack of consensus on what the evidence-based essential building blocks of implementation are.
   

Objective:
     
     We aimed to evaluate the evidence base supporting telemedicine implementation knowledge tools; identify shared conceptual constructs and outliers; and formulate recommendations to guide the design, development, and optimization of telemedicine services.
   

Methods:
     
     We conducted implementation research using a rapid umbrella review, that is, an overview of systematic reviews, in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). In total, we searched 3 databases (PubMed, Web of Science, and Scopus) for studies focusing on telemedicine implementation frameworks, models, and tools, collectively referred to as "knowledge tools." Reviews meeting the operational definition of a systematically undertaken, secondary evidence synthesis, such as systematic and scoping reviews, and those published from January 2018 to May 2024 were considered. A meta-aggregative qualitative analysis was undertaken, comprising inductive thematic synthesis.
   

Results:
     
     In total, 18 reviews were selected, encompassing 973 primary studies. Global perspectives were reflected in 61% (n=11) of the reviews, while 33% (n=6) focused on low- and middle-income country contexts. The primary research included in the reviews represented 63 countries, spanning the Americas, Europe, Africa, the Middle East, and Asia and the Pacific. Findings indicated substantial heterogeneity across the identified telemedicine implementation theories, models, and frameworks. However, following evidence synthesis, considerable convergence was observed, highlighting a state-of-the-art understanding of the essential requirements for a national telemedicine implementation ecosystem. These were categorized into "process" and "thematic" dimensions. Process dimensions included readiness and needs assessment, road map and planning, managing change, implementing telemedicine services, and continuous improvement and measuring performance. Thematic dimensions covered human and sociocultural aspects; organization, operations, management, and leadership; communication and coordination; policy, legal, and financial considerations; clinical health condition and quality of care; and the wider context.
   

Conclusions:
     
     The findings of this study inform a pressing translational research knowledge gap in telemedicine implementation, hindering the implementation of high-quality, sustainable, and scalable telemedicine systems. The study contributes to building global consensus on the state of the art of key constructs in telemedicine implementation and recommends that future research focus on field-testing the evidence-based implementation tools to evaluate their usability and adaptability across diverse telemedicine contexts.