Background: One of the complications that patients in need of home healthcare might experience is pressure injury. Given that a significant part of the care of these patients is performed by their family caregivers, they must have sufficient knowledge about prevention and treatment of pressure injuries. Methods: We investigated the knowledge related to pressure injuries among family caregivers of patients needing home care who were at risk of pressure injury. Family caregivers of patients in Iran who needed home care services and were at risk of developing pressure injuries based on the Braden scale were invited to participate. A special questionnaire designed by Arboledas and Pancorbo-Hidalgo was used to assess the caregivers' level of knowledge. This questionnaire consists of 23 items, and with total scores between 23 and 46. A higher score indicates a higher level of knowledge about pressure injuries. A total of 323 family caregivers participated, most of whom were female. Results: The mean total score of caregivers' knowledge about pressure injuries was 34.5 ± 3.4 (ranging 23 to 42). Most of the participants (n = 290) stated they did not receive adequate education related to pressure injuries. Among the demographic variables, a significant relationship was observed between the level of caregivers' knowledge with the level of education, younger age, offspring, admission in intensive care units, and male sex (p < 0.005). Conclusions: Family caregivers did not have sufficient knowledge about pressure injuries. Most of them did not receive the necessary education during the time of their patient's hospitalization. This issue should be considered by healthcare providers, and the necessary interventions should be considered to improve the situation.