Background/Objectives: Nutrition plays a significant role in preventive medicine, as up to 80% of chronic diseases could be avoided by adhering to healthy dietary principles. The aim of our study was to identify dietary habits, awareness, and nutrition knowledge in a random sample of Polish healthcare students and professionals. Methods: Initially, a total screened sample consisted of 1287 respondents, yet the actual response/participation rate was 634/1287. A validated questionnaire for the Polish population, the Dietary Habits and Nutrition Beliefs Questionnaire (KomPAN), was used for the assessment. Results: The majority of respondents were females (84.2% of medical students and 87.2% of healthcare professionals), current non-smokers (79.6% of medical students and 85.2% of healthcare professionals), and had a normal waist circumference (76.3% of medical students and 63.1% of healthcare professionals). Both clinical dieticians and students studying clinical dietetics received significantly different scores of dietary indexes (pro-healthy pHDI-10 and non-healthy nHDI-14) vs. respective groups of respondents. Both healthcare students and professionals who self-reported better nutritional knowledge indeed yielded significantly better results in the dietary indexes as well as nutritional knowledge scores. The nutrition knowledge score was positively correlated with pHDI-10 and negatively correlated with nHDI-14, BMI, age, and waist circumference. Conclusions: Our results illustrate lifestyle trends among Polish healthcare students and professionals, and such results should encourage the development of evidence-based dietary policies targeting healthcare providers. High-quality continuing nutrition education should be obligatorily provided to all healthcare providers to enhance their dietary awareness as well as ensure high quality of care and outcomes achieved by the Polish healthcare system.