Institutional objection (IO) occurs when institutions providing health care claim objector status and refuse to provide legally permissible health services such as abortion. IO may be regulated by sources including law, ethical codes and policies (including State and local/institutional policies). We conducted a mixed-methods narrative review of the empirical evidence exploring IO to abortion provision globally, to inform areas for further research. MEDLINE (Ovid), Embase (Ovid), CINAHL (EBSCO), Global Health (CAB Abstracts), ScienceDirect and Scopus were searched in August 2021 using keywords including ‘conscientious objection’, ‘faith-based organizations’, ‘religious hospitals’ and ‘abortion’. Eligible research focused on clinicians’ attitudes and experiences of IO to abortion. The 28 studies included in the review were from nine countries: United States (19), Chile (2), Turkey (1), Argentina (1), Australia (1), Colombia (1), Ghana (1), Poland (1) and South Africa (1). The analysis demonstrated that IO was claimed in a range of countries, despite different legislative and policy frameworks. There was strong evidence from the United States that clinicians in religious healthcare institutions were less likely to provide abortions and abortion referrals, and that training of future abortion providers was negatively affected by IO. Qualitative evidence from other countries showed that IO was claimed by secular as well as religious institutions, and individual conscientious objection could be used as a mechanism for imposing IO. Further research is needed to explore whether IO is morally justified, how decisions are made to claim IO, and on what grounds. Finally, appropriate models for regulating IO are needed to ensure the protection of women’s access to abortion. Such models could be informed by those used to regulate IO in other contexts, such as voluntary assisted dying.