Background: During the COVID-19 pandemic, it has been necessary to deliver mental health care using technologies (e-mental health). But there have been difficulties in its application. Quantitative systematic reviews such as meta-analysis doesn't allow us to fully identify and properly describe this subject. Thus, our study has two main objectives: a) "to determine what evidence is available for synchronous e-mental health implementation"; and b) "to develop a framework informed by a realist analysis for the implementation of synchronous e-mental health". Methods: We will search MEDLINE, EBM Reviews, PsycINFO, EMBASE, SCOPUS, CINAHL Complete, and Web of Science databases from 1st January 2015 to September 2020, with no language restriction. A systematic review with a narrative description and a realist synthesis will be conducted. Primary studies relating to adults with common mental health problems using any type of mobile mental health intervention that includes a synchronic component and communication with a mental health professional will be included. For the analysis, we will make a realist synthesis of the systematic reviews, using a grounded theory approach with an emergent approach to synthesize the information, prioritizing the systematic reviews with a lower risk of bias in the AMSTAR-2 tool. The realist synthesis will be based on the interpretation, integration, and inference of the evaluated elements and the generation of hypotheses to better understand the implementation process of synchronous e-mental health. Finally, we will present the overall assessment in a Summary of Qualitative Findings table. Conclusion: Our results will allow a better understanding of the facilitator and limitations in implementing e-mental health.