Pietro Lazzari was born in Rome, on May 15, 1898. At the age of 15, he was apprenticed to Roman sculptor, Jerace. Four years on the Italian front in World War I interrupted his studies, until he could return to the Ornamental School of Rome, where he received a Master Artist degree in 1922. Lazzari's first solo exhibition was at the Theatre of the Independents in Rome. He was also employed by newspaper Il Messaggero to illustrate articles with athletes' portraits.
Lazzari visited the United States in 1925, exhibiting in a group show at the New Gallery in the New York the following year. He also married American social worker Elizabeth Paine in 1926. After four more trips between the United States and Italy, he permanently settled in New York City in 1929. In addition to participating in major art exhibitions, he was hired by a New York newspaper to make courtroom sketches at the Lindbergh kidnapping trial. Divorcing his first wife in 1932, Lazzari married Evelyn Cohen in 1934, and became a U.S. citizen in 1936. Between 1936 and 1942, he worked on four post office murals for the U.S. Section of Fine Arts and began experimentation that led to his own method of painting in polychrome concrete.
In 1942, Lazzari moved to Washington, D.C. and participated in the war effort. He also taught painting and sculpture at The American University, and from 1948 to 1950, he headed the Art Department at Dumbarton College. In 1950, he received a Fulbright Fellowship for research in techniques of Etruscan Art.
Lazzari is known for his bronze busts of humanitarians, most notably Pope Paul VI, Adlai Stevenson, and Eleanor Roosevelt. Represented by the Betty Parsons Gallery in New York, he was also very active in the Washngton, D.C. art community, where he was represented by the Caresse Crosby Gallery.
Pietro Lazzari died on May 1, 1979 in Bethesda, Maryland.