This paper presents the results of a systematic scoping literature review of higher education mathematics and statistics support (MSS) evaluation focusing on its impact on students. MSS is defined as any additional organised mathematical and/or statistical aid offered to higher education students outside of their regular programme of teaching by parties within the students' institution specifically assigned to give mathematical and/or statistical support. The objective of this review is to establish how MSS researchers investigate the effect of MSS on students and what that impact is. Based on a predefined protocol, five databases, the proceedings of eight conferences, two previous MSS literature reviews' reference lists, and six mathematics education or MSS networks' websites and reports were searched for publications in English since 2000. A two-round screening process resulted in 148 publications being included in the review which featured research from 12 countries. Ten formats of MSS, seven data sources (e.g., surveys), and 14 types of data (e.g., institution attainment, usage data) were identified with a range of analysis methods. Potential biases in MSS research were also considered. The synthesised results and discussion of this review include the mostly positive impact of MSS, issues in MSS evaluation research thus far, and rich opportunities for collaboration. The role MSS has and can play in mathematics education research is highlighted, looking towards the future of MSS evaluation research. Future directions suggested include more targeted systematic reviews, rigorous study design development, and greater cross-disciplinary and international collaboration.