Peer mentoring is a widely employed strategy in higher education to foster student development and integration. However, the effectiveness of peer mentoring in higher education lacks well-established statements. A systematic review was conducted to assess the efficacy of peer mentoring during the initial phase of academic studies. This review evaluated effectiveness based on four outcomes: intention to drop out, the sense of belonging, academic and social integration. It also scrutinised gender disparities and distinctions between digital and non-digital, and group-based and individual peer mentoring. The review revealed that peer mentoring is an effective support mechanism, yielding favourable impacts across various outcomes: social and academic integration, career benefits, emotional benefits, soft skills, university-life balance, study dropout intention and sense of belonging to university. Gender disparities were generally inconspicuous in most studies. Digital peer mentoring proved effective, though students reported reduced levels of social support compared to non-digital peer-mentoring. Both individual and group-based peer mentoring programmes were utilised, but specific outcomes distinguishing the two formats were not discerned. In summary, peer mentoring proves to be a valuable resource for first-year students, particularly concerning academic and social integration. To holistically address the diverse needs of first-year students additional approaches may be considered.