He was born in Chile. He was son of Ambrose O'Higgins, the Ireland-born governor of Chile under Spanish rule.
Bernardo spent the earlier years of his life with his mother's family in south Chile. With his father he had a distant relation: he supported the son financially and was concerned of his education but never knew him. The Spaniards goverment officials in America were forbidden to marry locals.
As Ambrose O'Higgins became viceroy of Peru, Bernardo was sent to London to complete his studies. In this city Bernardo took knowledge of American-independist ideas: he knew Venezuelan Francisco de Miranda and joined the Logia Lautaro.
In 1810 he joined the nationalist rebels who desired independence from Spain. In 1814 his Chilean rebels were defeated by the Spanish and retreated into the Andes. In 1817 O'Higgins went back on the offensive with the aid of Argentine General José de San Martín. On 12 February, 1817 he led a cavalry charge that won the Battle of Chacabuco.
He became the first leader of independent Chile, and was granted dictatorial powers. However he wished to establish democracy and make various reforms (like abolishing nobility titles), which was resisted by the powerful conservative large land owners. He was deposed by conservative coup in 1823.
O'Higgins spent the rest of his life in Lima, Peru.
See also: History of Chile