Interest in probiotic use has surged in past decades and the current evidence-base suggests clinical benefits of many probiotic strains. Given the industry’s expansion, it is likely that patients will continue to seek guidance from healthcare providers about probiotics. Therefore, healthcare providers should be knowledgeable about how and when to recommend probiotics. The purpose of this systematic review was to understand how knowledge and attitudes impact physicians, nurses, and pharmacists (PNPs) in their probiotic recommendation behaviour. MEDLINE, EMBASE, Web of Science, CINAHL and PsycINFO were systematically searched from inception until December 17, 2021. Title/abstract and full-text screening, along with quality assessment using the JBI's Critical Appraisal Checklist for Analytical Cross-Sectional Studies, were conducted independently and in duplicate. Seventeen studies were included; all were cross-sectional surveys. PNPs generally had good knowledge and/or could provide the definition of probiotics. Pharmacists possessed the most knowledge. Physicians and pharmacists conveyed positive attitudes about the safety, efficacy, and clinical role of probiotics, while nurses’ attitudes were not reported. The majority of PNPs stated that they lacked experience and/or would not recommend probiotics to their patients, however, probiotics were regularly recommended for less severe conditions, like bloating and diarrhea. Common barriers preventing recommendation included a lack of supporting information and a perceived lack of efficacy. Our findings demonstrate that PNPs made limited probiotics recommendations. Limited evidence was identified on how knowledge of probiotics was acquired or applied. Future research should investigate the inclusion of probiotics in PNP curricula and scope of practice.