Systematic reviews are an important and necessary source of information to improve healthcare delivery; however, reviews of the existing research are often insufficient to address the decision-making needs of health systems. Incorporating data from health systems into traditional systematic reviews may be one way to improve their utility. In this paper, we map out ways in which health system data can be used with systematic reviews, articulate the scenarios for when health system data may be most helpful to use alongside systematic reviews (i.e., to improve the strength of evidence, to improve the applicability of evidence, and to improve the implementation of evidence), and discuss the importance of framing the limitations and considerations when using unpublished health system data in reviews (i.e., critical appraisal to understand the study design biases as well as limitations in information and data quality). To develop this framework, we used examples identified through literature searches and affiliations with four health systems that have the ability to use both internal and external evidence to support their clinical operations. Finally, we also offer recommendations to systematic reviewers who choose to integrate health system data and possible next steps in developing processes and capacity to routinely conduct this type of work.