Lorenzo Homar was born in 1913 in San Juan, Puerto Rico. During his childhood, he was surrounded by art, as his father was a patron of the arts and his mother, a pianist. In 1928, Homar had to drop out of high school due to economic problems and worked at a textile factory. In 1931, he attended the Art Students League in New York under the direction of George Bridgman. He then joined Cartier as an apprentice designer, while simultaneously studying at the Pratt Institute. He voluntarily enlisted in the army for World War II and used his drawing skills to perform military maps and sketches.
After the war, he returned to Cartier in 1946 and studied at the School of Art in Brooklyn. He returned to Puerto Rico in 1950, where he founded the Center for Puerto Rican Art. In 1952, he became the director of the Taller de Gráfica de la División de Educación a la Comunidad. During the 1960s, he worked with graphic printing, especially screen printing. He is noted for designing the logo of the VIII Pan American Games in 1979 and for the Instituto de Cultura Puertorriqueña.
In 1978 he was awarded an honorary doctorate from the University of Puerto Rico. He died in 2004 in San Juan Puerto Rico. Today, he is still considered by many to be Puerto Rico's greatest graphic designer.