Maharana Udai Singh (August 4, 1522 – February 28, 1572) was a king of Mewar and the founder of the city of Udaipur in the present day Rajasthan state of India. He was the 53rd ruler of the Mewar dynasty. He was the fourth and posthumous son of Maharana Sangram Singh and Rani Karmavati, a princess of Bundi.
Udai Singh was born in Chittor. In January, 1528 after the death of his father, Maharana Sangram Singh, he was succeeded by his eldest surviving son, Maharana Ratan Singh. Ratan Singh was assassinated in 1531. He was succeeded by his brother Maharana Vikramaditya Singh. During his reign, when the Sultan of Gujarat Bahadur Shah sacked Chittor in 1534, Udai Singh was sent to Bundi for safety. In 1537, Banbir killed Vikramaditya and usurped the throne. He tried to kill Udai Singh also, but Udai's nurse Panna Dhai sacrificed her own son to save him from his uncle Banbir and took him to Kumbhalgarh. He lived in secret in Kumbhalgarh for two years, disguised as a nephew of the governor Asha Shah. In 1540, he was crowned in Kumbhalgarh by the nobles of Mewar. His eldest son Maharana Pratap was born in the same year. He had twenty wives and twenty-five sons.