This case study aims to report on the psychological assessment and intervention for a 4-year-old preschooler with selective mutism. A comprehensive assessment that involves parents and teacher interview, classroom observation, Seguin Form Board Test (SFBT), Vineland Adaptive Behaviour Scales Third Edition (Vineland-3), Behaviour Assessment System for Children, Third Edition (BASC-3), Childhood Autism Rating Scale, Second Edition Standard Version Rating Booklet (CARS 2-ST), and School Speech Questionnaire were conducted. The psychological assessment revealed that the child fulfils the criteria for selective mutism. Play-based intervention sessions were then conducted, which involved gradual exposure to the child's teacher and peers and facilitation of verbalization related to child's interests and classroom routines. The child demonstrated improvement in her frequency of verbalizing in the classroom following the intervention, as supported by the improved score in the School Speech Questionnaire (SSQ). This case study illustrates the advantages of a collaborative approach that engages parents, teachers, and peers in the management of selective mutism during early childhood.