Harilal was born on 23 August 1888 while his father was in England for higher studies. He too wanted to go to England for higher studies and hoped to become a barrister as his father had once been. His father firmly opposed this, believing that a Western-style education would not be helpful in the struggle against British rule over India. Eventually rebelling against his father's decision, in 1911 Harilal renounced all family ties.
In June 1935, Mahatma Gandhi wrote a letter to Harilal, accusing him of "alcohol and debauchery". In the letters, Mahatma Gandhi stated that Harilal's problems were more difficult for him to deal with than the struggle for Indian republic.
However, later in 1936, on his mother Kasturba Gandhi's request he converted back to Hinduism through the Arya Samaj and adopted a new name, Hiralal.
Harilal died of tuberculosis four months after Gandhi’s death on the night of June 18 at the age of 59. Being alcoholic he was racked by liver disease, and possibly syphilis. But records at the Sewri Hospital suggest that he died a lonely death. Harilal’s death certificate is preserved at the BMC’s archives in Vakola. It mentions 8 pm on June 18, 1948, as the time of death. There is no mention of any family members on the document, but it reveals that he was admitted to the hospital after being found unconscious in Kamathipura.
The troubled relationship between Harilal and his father is the subject of the film and play Gandhi, My Father. The film adaptation was released on 3 August 2007 and directed by Feroz Abbas Khan and produced by Anil Kapoor. Harilal is portrayed by Akshaye Khanna. Khan's play, Mahatma vs. Gandhi, while different from this film, had a similar theme. There is also a Marathi play named Gandhi virudh Gandhi.
Harilal was married to Gulab Gandhi and they had five children, two daughters, Rani and Manu, and three sons, Kantilal, Rasiklal and Shantilal. Rasiklal and Shantilal died at an early age. He had four grandchildren (Anushrya, Prabodh, Neelam and Navmalika.) via Rani, two (Shanti and Pradeep) via Kanti, and one (Urmi) via Manu. He became detached from his children after Gulab’s death in a flu epidemic.