Background Cancer cachexia (CC) is a debilitating syndrome severely impacting patients’ quality of life and survivorship. We aimed to investigate the health care professionals’ (HCPs’) experiences of dealing with CC. Methods Survey questions entailed definitions and guidelines, importance of CC management, clinician confidence and involvement, screening and assessment, interventions, psychosocial and food aspects. The online survey was disseminated through Australian and New Zealand palliative care, oncology, allied health and nursing organisations. Frequencies were reported using descriptive statistics accounting for response rates. Associations were examined between variables using Fisher’s exact and Pearson’s chi-square tests. Results Over 90% of the respondents (n = 192) were medical doctors or nurses. Over 85% of the respondents were not aware of any guidelines, with 83% considering ≥ 10% weight loss from baseline indicative of CC. CC management was considered important by 77% of HCPs, and 55% indicated that it was part of their clinical role to assess and treat CC. In contrast, 56% of respondents were not confident about managing CC, and 93% believed formal training in CC would benefit their clinical practice. Although formal screening tools were generally not used (79%), 75% of respondents asked patients about specific symptoms. Antiemetics (80%) and nutritional counselling (86%) were most prescribed or recommended interventions, respectively. Conclusion This study underlines the deficiencies in knowledge and training of CC which has implications for patients’ function, well-being and survival. HCP training and a structured approach to CC management is advocated for optimal and continued patient care.