Introduction: Internalized HIV stigma remains a significant barrier to successful care retention for people living with HIV (PLHIV). Stigma has been felt as shame, guilt, and self-blame, dampening adherence to antiretroviral therapy (ART) and clinic attendance. Aim: The aim of this study was to explore the impact of internalized HIV stigma on care retention among individuals living with HIV at Chifundo Clinic in Lusaka District, Zambia. Methods: Cross-sectional analytical study with 384 participants aged 18 years and above having been in care for more than six months. Data were collected via an online Kobo Toolbox to measure internalized stigma, demographic variables, and care retention. Logistic regression analysis was used in testing the association between internalized stigma and clinic visitation. Results: Over 75% of the participants had once missed clinic a visit, of whom 5% had previously been declared as no longer in care (NLIC). Internalized stigma measures showed that 26% of the participants very often self-shamed due to HIV status and 31% very often felt guilty. Participants who self-blamed were 70% more likely to miss a clinic visit. Those who feared disclosing their status were 8 times likely to miss a clinic visit. Conclusion: Internalized HIV stigma is a key driver of retention in care among PLHIV at Chifundo Clinic. Stigma reduction is essential using combined, culture-tailored interventions and psychosocial support. Stigma reduction should be policymakers' and healthcare providers' number one priority to increase ART adherence, retention, and yield better health outcomes for PLHIV in Zambia.