The Tyrrhenian tree frog (Hyla sarda) is a small cryptically coloured amphibian found in Corsica, Sardinia, and the Tuscan Archipelago. Investigation into the species' evolutionary history has revealed phenotypic changes triggered by glaciation-induced range expansion, but understanding the genetic basis of this trait variation has been hampered by the lack of a reference genome. To address this, we assembled a chromosome-level genome of Hyla sarda using PacBio HiFi long reads, Bionano optical maps, and Hi-C data. The assembly comprises 13 assembled chromosomes, spanning a total length of 4.15 Gb with a scaffold N50 of 385 Mb, a BUSCO completeness of 94.60%, and a k-mer completeness of 98.30%. Approximately 75% of the genome consists of repetitive elements. We annotated 22,847 protein-coding genes with a BUSCO completeness of 94.60% and an OMArk completeness of 93.74%. This high-quality assembly provides a valuable resource for studying phenotypic evolution and its genomic basis during range expansion, and will assist future investigations into the population and conservation genomics of Hyla sarda.