Nutrition is a key component of care for critically ill patients; yet nutrition delivery is below international recommendations. In order to improve nutrition delivery to critically ill patients, an understanding of the barriers that prevent guideline adherence is required. It is known that clinicians' knowledge, attitudes, and beliefs of the role of nutrition may act as a potential barrier to nutrition delivery, but whether this remains true in critical care is unknown. The aim of this systematic scoping review was to summarize the literature exploring the knowledge, attitudes, and beliefs of clinicians around nutrition support in critically ill patients. A search of four online databases (MEDLINE via Ovid, Emcare via Ovid, PsycINFO, and CINAHL via EBSCOhost) was conducted on August 14, 2020, to identify literature that reported on clinicians' knowledge, attitudes, and beliefs of nutrition in adult intensive care patients. Data were extracted on study and participant characteristics, methodology, and key study outcomes related to nutrition. Eighteen articles met eligibility criteria and were included in the review. Key findings included the following: nutrition was seen as a priority that ranked below life-saving interventions; differences in perceived clinician responsibilities exist; common barriers to nutrition delivery included inadequate resourcing, lack of nutrition protocols, and gastrointestinal intolerance; and identified facilitators included nutrition education and the presence of a supportive multidisciplinary team. The implementation of nutrition protocols, enhanced clinical nutrition education, and further clarification of roles and responsibilities pertaining to nutrition may assist in improving nutrition delivery in critical care.