The son of the former Chilean president Manuel Montt (Montt, Manuel), Pedro Montt graduated in law from the National Institute in 1870. He was elected a member of the Chamber of Deputies in 1876 and became its president in 1885. Montt held two posts in the cabinet of President José Balmaceda (Balmaceda, José Manuel), but he later (1891) took an active part in the revolution that overthrew Balmaceda. He then went to the United States, first as an agent of the revolutionary junta and later (after U.S. recognition) as minister from Chile.

Unsuccessful in his first bid for the presidency (1901), Montt was elected by a large majority in 1906 as the candidate of the National Union ticket. His first action was to call out the army to suppress large-scale strikes (1907). His administration supported the construction of a railway that ran the length of the country and stimulated the production of nitrates and copper. It did little, however, to improve the living conditions of the people. In 1910 Montt left Chile for medical treatment in Germany, where he died.