Was born in Singapore in 1893, where his father, Javala Singh, of the village of Dhardeo (Amritsar district), was employed as a gunner in the army. Santokh Singh had his early education in a school in Singapore and learnt. Punjabi (Gumukhi script) at home from his father. For higher education he came to the Punjab and joined the Khalsa College at Amritsar, from where he passed the Entrance examination in 1910. He gave up his studies and went to the United Stated of America in 1912 where he came in contact with Sant Vasakha Singh and Bhai Javala Singh, who were owners of potato ranclies and were working for the freedom of India.

Santokh Singh joined the Ghadr movement and in a short time had himself elected as the general secretary of the party. He visited Siam (Thailand), Burma and Shanghai for the purpose of collecting money and arms to raise in India an armed rebellion against the British. Santokh Singh was arrested along with some other Ghadr leaders in the San Francisco conspiracy case, and sentenced in April 1918 to 21 months imprisonment. As the (1radr revolt was crushed by the government with a heavy hand, Santokh Singh turned towards Soviet Russia to work out a new strategy for continuing the struggle for the liberation of India. He, along with Bhai Ratan Singh, travelled secretly, sometime in the summer of 1922, to Soviet Russia where both of them underwent training at M.N. Roy's Communist. University of the Toilers of the East. They attended the 4th Congress of the Communist International from 5 November to 5 December 1922, met Communist leaders from various countries and exchanged views with them. Resolved to start a revolutionary journal in the Punjab, Santokh Singh left Russia in May 1923 to return home. It was a hazardous journey for hire. Before reaching India, he was put under arrest. The case against him lingered for about a year and then he was bound down for good behaviour for one year in his village, Dhardeo. In 1926, Bhai Santokh Singh launched from Amritsar the Kirti, a Punjabi monthly dedicated to the cause of workers and peasants. But he had not long to live. He fell a victim to tuberculosis and died in 1927 when he was only thirty-four.