She was the princess of Ramnad, and the daughter of Chellamuthu Sethupathy. She married the king of Siva Gangai and they had a daughter - Vellachi Nachiar. When her husband was killed, she was drawn into battle. Her husband and his second wife were killed by a few British soldiers and the son of the Nawab of Arcot. She escaped with her daughter, lived under the protection of Hyder Ali at Virupachi near Dindigul for eight years. During this period she formed an army and sought an alliance with Gopala Nayaker and Hyder Ali with the aim of attacking the British. In 1780 Rani Velu Nachiyar fought the British with military assistance from Gopala Nayaker and Hyder Ali and won the battle. Rani Velu Nachiyar formed a woman's army named “udaiyaar” in honour of her adopted daughter — Udaiyaar, who died detonating a British arsenal. Nachiar was one of the few rulers who regained her kingdom and ruled it for 10 more years.
The Queen Velu Nachiar granted powers to Marudhu Brothers to administer the country in 1780. Velu Nachiar died a few years later, but the exact date of her death is not known (it was about 1790). Marudu brothers are the sons of Udayar Servai alias Mookiah Palaniappan Servai and Anandayer alias Ponnathal. They are native of Kongulu street of Ramnad. They belonged neither to the family of the ancient poligars nor to their division of the caste.