On September 28, 1907, Bhagat Singh was born into a Sandhu family to Sardar Kishan Singh Sandhu and Vidyavati in the Khatkar Kalan village near Banga in the Lyallpur district of Punjab. Singh's given name of Bhagat meant "devotee", and his surname meant "lion". His family background was that of a patriotic Sikh family which had participated in numerous movemements supporting independence of India. His father was influenced by the Hindu reformist Arya Samaj. His uncles, Ajit Singh and Swaran Singh, as well as his father were both part of the Ghadr Party led by Kartar Singh Sarabha. Ajit Singh was forced to flee to Iran because of pending cases against him while Swaran Singh was hanged.
As a child, he was deeply affected by the Jalianwala Bagh Massacre that took place in Punjab in 1919. When Mahatma Gandhi started the Non-Cooperation Movement in 1920, he became an active participant at the age of 13. He had great hopes that Gandhi would bring freedom in India. But he was disappointed when Gandhi called off this movement following the Chauri Chaura riot in 1922. At this point he had openly defied the British and had followed Gandhi's wishes by burning his government-school books and any British-imported clothing. In 1923, Bhagat famously won an essay competition set by the Punjab Hindi Sahitya Sammelan. This grabbed the attention of members of the Punjab Hindi Sahitya Sammelan including its General Secretary Professor Bhim Sen Vidyalankar. At this age, he quoted famous Punjabi literature and discussed the Problems of the Punjab. He read a lot of poetry and literature which was written by Punjabi writers and his favourite poet was an Indian freedom fighter Allama Iqbal from Sialkot. In his teenage years, Bhagat Singh started studying at the National College in Lahore, but ran away from home to escape early marriage, and became a member of the organization Naujawan Bharat Sabha (Translated to 'Youth Society of India'). In the Naujawan Bharat Sabha, Singh and his fellow revolutionaries grew popular amongst the youth. He also joined the Hindustan Republican Association at the request of Professor Vidyalankar, which was then headed by Ram Prasad Bismil and Ashfaqulla Khan. It is believed that he had knowledge of the Kakori train robbery. He wrote for and edited Urdu and Punjabi newspapers published from Amritsar. In September 1928, a meeting of various revolutionaries from across India was called at Delhi under the banner of the Kirti Kissan Party. Bhagat Singh was the secretary of the meet. His later revolutionary activities were carried out as a leader of this association. The capture and hanging of the main HRA Leaders also allowed him and Sukhdev to be quickly promoted to higher ranks in the party.