The onset of a chronic physical health condition (CHC) can highly impact individuals' well-being and mental health. Social support has been shown to help people rebound after the onset of a CHC. Nonetheless, little is known about the longitudinal pattern of social support and its reciprocal association with mental health in CHC. This study aimed to illustrate the longitudinal pattern of perceived social support and to examine the reciprocal association between perceived social support and psychological distress across 6 years. Two random intercept cross-lagged panel models were conducted, one for emotional and one for practical support, using yearly assessments of 582 Swiss Household Panel's participants reporting a CHC. A reciprocal association was found, with psychological distress 1 year after the onset being linked to less emotional support in the following year and vice versa, more emotional support being linked to less psychological distress the following year. A unidirectional association was found for practical support, with more psychological distress 1 year before the CHC onset being linked to more practical support at the onset year. This study underlines the importance of involving the social environment of individuals living with a CHC, especially around the first year after the onset.