Abstract Objective Pediatric psychologists have unique expertise to contribute to the care of youth with serious illnesses yet are not routinely integrated into pediatric palliative care (PPC) teams. To better define the role and unique skillset of psychologists practicing in PPC, support their systematic inclusion as part of PPC teams, and advance trainee knowledge of PPC principles and skills, the PPC Psychology Working Group sought to develop core competencies for psychologists in this subspecialty. Methods A Working Group of pediatric psychologists with expertise in PPC met monthly to review literature and existing competencies in pediatrics, pediatric and subspecialty psychology, adult palliative care, and PPC subspecialties. Using the modified competency cube framework, the Working Group drafted core competencies for PPC psychologists. Interdisciplinary review was conducted by a diverse group of PPC professionals and parent advocates, and competencies were revised accordingly. Results The six competency clusters include Science, Application, Education, Interpersonal, Professionalism, and Systems. Each cluster includes essential competencies (i.e., knowledge, skills, attitudes, roles) and behavioral anchors (i.e., examples of concrete application). Reviewer feedback highlighted clarity and thoroughness of competencies and suggested additional consideration of siblings and caregivers, spirituality, and psychologists’ own positionality. Conclusions Newly developed competencies for PPC psychologists highlight unique contributions to PPC patient care and research and provide a framework for highlighting psychology’s value in this emerging subspecialty. Competencies help to advocate for inclusion of psychologists as routine members of PPC teams, standardize best practices among the PPC workforce, and provide optimal care for youth with serious illness and their families.