To report the occurrence of unilateral, neonatal-onset congenital glaucoma in a child with Rubinstein-Taybi Syndrome (RTS). A 15-day-old male with features of RTS was presented with an enlarged corneal diameter, corneal haze, and peripheral corneal vascularization of the left eye. Ultrasound biomicroscopy of his left eye revealed iris atrophy, iridocorneal adhesions, and iris adhesions to a partially absorbed cataractous lens. Genetic evaluation of the child and the parents revealed a novel de novo heterozygous pathogenic variant in exon 5 of the CREBBP gene (NM_004380.3:c.1390C>T). A diode laser cyclophotocoagulation was performed to control the IOP in the left eye. Unilateral neonatal-onset congenital glaucoma due to iridocorneal adhesions can be a rare presentation of Rubinstein-Taybi Syndrome.