Rising domestic burdens for mothers fueled concerns that the COVID-19 pandemic exacerbated gender inequalities in well-being. Yet, survey research has not considered whether and how cognitive labor—planning, organizing, and monitoring family needs—contributed to gendered health disparities during the pandemic. Using data from the Study on U.S. Parents’ Divisions of Labor during COVID-19 (SPDLC) and a stress process perspective, we examine the association between cognitive labor and parents’ psychological well-being, and whether this association (1) differs between mothers and fathers and (2) is moderated by employment status and telecommuting. Mothers performed more cognitive labor during the pandemic than fathers, and cognitive labor was negatively associated with mothers’ psychological well-being—particularly for mothers who never or exclusively telecommuted. Mothers’ psychological well-being was higher when fathers did more cognitive labor, especially among mothers who worked outside the home. Overall, cognitive labor appears to be another stressor that contributed to increased gender inequality.