Bloch was a Philadelphia painter and art instructor, best known for his social realist depictions of everyday life. Born in Germany, Bloch came to the United States as a boy, settling in Philadelphia. He attended Central High School. Though his family had little money, his mother encouraged his artistic ambitions. Bloch studied at the School of Industrial Art and the Pennsylvania Academy of the Fine Arts, under Thomas Anshutz. He later attended the school at the Barnes Foundation in Merion, Pennsylvania. He served in the Army during World War I. Bloch was involved in left-wing politics and worked for the New Deal Public Works of Art Project.
He dedicated himself to depictions of the underprivileged—in particular Philadelphia's African American community. According to the Woodmere Art Museum, Bloch was the first white artist to exhibit with the Pyramid Club and was praised in the Negro History Bulletin for "the intensity of his psychological character studies of the Negro."
He taught at the Pennsylvania Academy of the Fine Arts. In the 1950s, Byzantine mosaics he saw in Europe encouraged Bloch to begin painting brighter and more abstract pictures.
