BACKGROUND: Parents of infants identified with unilateral hearing loss (UHL) make decisions about managing their infant's hearing loss based on limited evidence and before knowing whether their infant will require additional support. OBJECTIVES: The decision-making processes of parents and clinicians regarding the management of UHL following newborn hearing screening were examined. PROCEDURE: Two convenience samples were recruited: 15 parents of children with permanent UHL aged under 4 years, and 14 clinicians. Applied thematic analysis of the semi-structured interviews elicited insight into the complexities surrounding decision-making from a parent and clinician perspective. RESULTS: Three main themes captured the decision-making process: motivation for decision-making, limited evidence creates uncertainty, and available evidence builds certainty. The diverse experiences and opinions of parents and clinicians highlight the complexity of decision-making when there are contested opinions and no clear best management option. CONCLUSIONS: The choices parents make about the management of their child's UHL can have lifelong implications for their child. Many questions need answering before parents can effectively evaluate the short- and long-term consequences of their options and whether the advantages outweigh the disadvantages in the long-term. This uncertainty is challenging for professionals and parents and risks cognitive biases influencing clinical and parental decision-making.