Background: Initiatives aimed at assessing and intervening in health literacy have the potential to promote adherence to self-care behaviours, which is the main focus of intervention by rehabilitation nurses. Thus, the objectives were to analyse the level of health literacy of working-age citizens and identify priority areas for intervention by rehabilitation nurses. (2) Methods: Quantitative, correlational and cross-sectional study, conducted in a multinational company, with the participation of 161 workers. The data were collected between 14 April and 7 May 2021, using a self-completion questionnaire composed of sociodemographic and clinical characterization and the European Health Literacy Survey, following a favourable opinion from the Ethics Committee and the company’s management. (3) Results: Overall, low to moderate literacy scores were predominant. Age and education were significantly associated with literacy scores. Workers with higher levels of health literacy had no diagnosed illnesses, took less medication, reported less sadness, fewer memory changes and less muscle and joint pain. (4) Conclusions: The fact that higher levels of health literacy trigger self-care behaviours and, consequently, fewer health problems reinforces the need for rehabilitation nurses to invest in this area.