Too few children receive the mental health care that they need. This cross-sectional study aimed to investigate the non-perception of children's mental health problem care needs among parents of children aged 3 to 17 years identified as having mental health difficulties (MHDs) and to explore the associated factors. In the French random population-based EpiCov study, 21,092 parents reported, for one randomly selected child, their perceptions of the child's needs for care and the child's MHDs using the Strengths and Difficulties Questionnaire (SDQ). Multivariable Poisson regression models were used. Among the participating parents, 57.6% were women, and 44.9% of their children were female. A total of 6,338 parents reported at least one abnormal SDQ subscale score pertaining to emotional problems, peer relationship problems, hyperactivity/inattention problems or conduct problems; however, 65.1% of these parents did not perceive their child to be in need of psychological care. The risk factors associated with the nonperception of the need for mental health care among both boys and girls included being a male parent, having a lower educational level, living in an area characterized by low access to primary care, and having no personal history of mental health conditions. Children who were younger than 5 years old faced a greater risk of an unrecognized need for mental health care, whereas the need for care exhibited by children who experienced a greater number of MHDs was less likely to remain unrecognized. These findings highlight the underperception of mental health difficulties among children and emphasize the importance of public health initiatives aimed at improving mental health literacy and access to care among parents.