AMAR SIṄGH, RĀJĀ (1748-1782), of Paṭiālā, was born on 6 June 1748, the son of Sardūl Siṅgh and Rāṇī Hukmāṅ. In 1765, he succeeded his grandfather, Ālā Siṅgh, who had no son living at the time of his death. His succession to the throne of Paṭiālā was challenged by his step-brother, Himmat Siṅgh, who seized a major portion of the town of Paṭiālā and the neighbouring area. Amar Siṅgh secured the eviction of Himmat Siṅgh through the help of the chiefs of Jīnd, Nābhā and Kaithal. In 1766, he captured Pāyal and Īsṛū from the Koṭlā Afghāns with the help of trans-Sutlej Sikhs under Jassā Siṅgh Āhlūvālīā, from whom he had received the rites of Khālsā baptism. Pāyal was annexed to Paṭiālā state, while Īsṛū was given to Jassā Siṅgh Āhlūvālīā.
Ahmad Shāh Durrānī's invasion of the country in 1767 proved very beneficial to the rising power of Amar Siṅgh, who sent his vakīls to the Shāh with presents. The Shāh summoned Amar Siṅgh and granted him the sūbahdārī (governorship) of Sirhind with the title of Rājā-i-Rājgān. He was also given a flag and a drum as insignia of absolute authority. He paid a lakh of rupees to the Shāh to secure the release of several thousand Hindus taken captive in the vicinity of Mathurā and Sahāranpur. He issued coins in the name of Ahmad Shāh.
In 1768, Amar Siṅgh marched against, Gharīb Dās of Manī Mājrā who, after the death of Ālā Siṅgh, had captured the fort and district of Piñjore. Amar Siṅgh, helped by the hill rulers of Hiṇḍūr, Kahlūr and Nāhan, defeated Gharīb Dās and captured the Piñjore fort. Gharīb Dās was, however, not fully reduced to submission. Rājā Amar Siṅgh marched against him again in 1778. Gharīb Dās paid a large sum of money to the Paṭiālā chief and retained control of his territory.
Amar Siṅgh next attacked the fort of Koṭ kapūrā, killing Jodh Siṅgh, the local chief, in the battle. In 1771, he occupied the district of Baṭhiṇḍā subduing Sukhchain Siṅgh to whom the Fort of Gobindgaṛh, commanding the town, belonged. Three years later, he reduced Saifābād, a strong fort 7 km to the north-east of Paṭiālā. In 1774, he occupied the Bhaṭṭī country lying south of Paṭiālā. Fatehābād, Sirsā and the fort of Raṇīā now passed into his hands. In 1777, he again overran Farīdkoṭ and Koṭ Kapūrā but did not attempt to annex them. In 1779, he frustrated the designs of Abdul 'Ahad Khān against Sikh territories in the Mālvā. He received help from Jassā Siṅgh Āhlūvālīā, Jassā Siṅgh Rāmgaṛhīā, Tārā Siṅgh Ghaibā and Jodh Siṅgh, of Wazīrābād, and repulsed the Mughal expedition at the village of Ghuṛām. By his extensive conquests and by the shrewd political alliances he made with the rulers of Nāhan and Bīkāner and with the Misldār sardārs, Amar Siṅgh had made Paṭiālā the most powerful state between the Yamunā and the Sutlej.
Rājā Amar Siṅgh died at Paṭiālā on 5 February 1782 in the prime of his youth.