PurposeThis study reviews post-2009 literature on public sector internal auditing (IA) and addresses three interrelated research questions (RQ): How is research on the public sector IA being developed? What are the focus and criticisms of the literature on public sector IA? What is the future of public sector IA research?Design/methodology/approachWe adopt a systematic literature review approach and analyze 78 peer-reviewed journal articles published between 2010 and 2019. We evaluate five criteria to identify the development of public sector IA research (RQ1), namely level of government, academic discipline, number of countries, geographic areas and MSCI country classification. Similarly, we use four criteria to present the focus and criticisms of the literature (RQ2), namely, type of organizational respondent, research instrument, theories and research theme examined. Finally, we use two criteria to propose new directions for future research (RQ3), namely, the directions resulted from RQ1 and RQ2 and the directions highlighted by the 10 most cited studies in the IA literature (i.e. out of the 78 papers identified).FindingsWe find an increase of publications up to 2017, most of which are single country–focused, particularly on emerging markets. Moreover, we note that IA has been studied at all government levels, most often at the local government level. Although we identify multiple research themes examined in the literature, most studies emphasize “governance” and “operational effectiveness” using quantitative analysis, without reference to any theory. By analyzing these key features, we critically interpret the challenges as well as the skepticism that may surface by researchers. Finally, considering implications from this stream of research and analyzing the most influential studies, we recommend new avenues for investigation such as comparative studies among countries and different markets that provide further evidence on the international and regional levels and studies on the effect of cultural, institutional and demographical characteristics in IA.Practical implicationsOur results will help researchers, practitioners and consultants to identify the key issues related with IA.Originality/valueThis study is the first to provide a systematic literature review on public sector IA. Furthermore, it develops insights, critical reflections and avenues for future research in this field.