Adequate nutrition before and during pregnancy, as well as postpartum, is among the major contributors to maternal and newborn health. Physiotherapists’ knowledge of this area is still scarce, although their clinical practice has been linked to newborns’ neuropsychomotor development, which, in turn, is influenced by maternal health and nutritional status. Therefore, this study aimed to evaluate the nutritional knowledge of physiotherapists regarding maternal and newborn health. A total of 70 Brazilian physiotherapists (32.2 ± 6.0 years; 72.9% females) were evaluated between November 2019 and February 2020 for their sociodemographic characteristics, professional experience, and nutritional knowledge about maternal and newborn health through a validated questionnaire personally administered by the same trained researcher. Most of the physiotherapists had graduated but had no specialization in maternal and child physiotherapy (96.1% of the females and all the males). The nutritional knowledge about maternal and newborn health was significantly different between the female and male health professionals, as well as between the less and more experienced participants, i.e., female physiotherapists and the more experienced ones had more correct answers on the nutritional questionnaire than the male and less experienced physiotherapists, respectively (p < 0.05). Our results open an interesting window for the future education and training of Brazilian physiotherapists in nutrition.