Cellular blue nevus is an uncommon neoplasm in the conjunctiva. Here we present an unusual case of a cellular blue nevus that clinically resembled conjunctival melanoma. A 29-year-old Chinese male was found to have a giant pigmented lesion of the conjunctiva around the limbal area of right eye from birth. Excisional biopsy with no-touch technique, lamellar corneal transplantation, amniotic membrane transplantation and adjuvant cryotherapy were performed. Histopathology revealed a nodular, well-defined tumor, which was composed of heavily pigmented dendritic cells and less pigmented spindle cells. There was no recurrence during eight years follow-up. Cellular blue nevus of conjunctiva can be wrongly diagnosed as conjunctival melanoma due to atypia criteria. Therefore, it is important to understand its clinical and pathological characteristics to avoid an overtreatment.