Background: School counselors address the social/emotional, academic, and career needs of students in the K-12 education system, including those who have a chronic illness. Estimates of the percentage of school-aged children and adolescents affected by a chronic physical illness in the United States range from 13 to over 40% (Health Resources and Services Administration, 2018). However, research on interventions related to the fostering of mental health in children and adolescents with a chronic illness is sparse in the K-12 setting. Objectives: The physical health needs of individuals with chronic illness often take precedence over their mental health needs (Lum et al., 2022). Therefore, our objective was to understand the ways in which school counselors support the mental health of K-12 students who have a chronic illness. Research Question: The research question that guided our inquiry was: “What are school counselors’ lived experiences supporting the mental health of students with chronic illness?”. Methods and Results: We utilized a phenomenological approach to understand the lived experiences of school counselors who are working to address the mental health needs of students with a chronic illness. The result was six themes: (a) lack of a universal definition for chronic illness in school systems/districts; (b) collaboration and communication; (c) advocacy; (d) varying degrees of awareness/understanding of the challenges students with chronic illness face; (e) varying expertise; and (f) interventions to address mental health needs. Conclusions: Our findings and implications highlight the need for further exploration into how school counselors can more intentionally support the mental health of chronically ill students within the K-12 school system, while also identifying the barriers that school counselors face when working to support these students.