Increased caregiving demands associated with raising an autistic child have resulted in reduced social support, increased stress, and decreased relationship satisfaction for mothers of autistic children compared to parents of neurotypical children. While social support is a protective factor against parental stress and can increase relationship satisfaction, few studies have examined the support networks, functions (e.g., instrumental, emotional, and informational) of perceived support, and associated mental health outcomes of mothers of autistic children. By understanding how and from whom mothers receive support, we can increase the dissemination of information (e.g., de-implementation of low-value practices) and enhance how support is provided (e.g., social media and community awareness and resources). This study aims to address these limitations by surveying 100 mothers of autistic children (ages 5–12 years old) to examine (1) who mothers identify as their primary support person, (2) the function of perceived support, (3) their stress, and (4) relationship satisfaction. This study is one of the first to have mothers self-identify who they primarily rely on for support, permitting the identification of previously unknown sources of support (e.g., non-spousal supports) to provide more nuanced insight into a mother’s support network and support preferences. The results of this novel study can elucidate the implications and outcomes of support networks, functions of perceived support, and stress on the relationship satisfaction of mothers of autistic children to examine the factors involved in developing more effective services to increase caregivers’ quality of life, a severely underfunded area of research. A comprehensive understanding of the factors (e.g., support) that influence the well-being of mothers of autistic children and how they care for themselves, their autistic child, and their family is increasingly important to promote and protect their relationships and sustain the energy needed for long-term advocacy on behalf of an autistic individual.