Congenital ranula cysts are rare, benign cysts that arise from the obstruction or rupture of the sublingual gland ducts in the oral cavity of newborns. Here, we present a case of a congenital ranula cyst in a newborn, highlighting the clinical presentation, diagnosis, and management of this rare condition. The neonate presented with a smooth, painless, and non-tender mass in the floor of the mouth, which was identified as a sublingual cyst via ultrasonography. The neonate underwent successful surgical excision of the cyst, with no complications or recurrence observed during the follow-up period. Congenital ranula cysts are a rare but treatable condition that can present in the oral cavity of newborns, and early diagnosis and surgical excision are crucial to prevent complications and ensure optimal outcomes. Healthcare providers should consider congenital ranula cysts as a differential diagnosis for any newborn presenting with a mass in the oral cavity.