Pihos played professional football as an end in the National Football League (NFL) for the Philadelphia Eagles from 1947 to 1955. While with the Eagles, he helped the team win back-to-back NFL championships in 1948 and 1949. He was selected six times to play in the Pro Bowl (1950–1955) and six times as a first-team All-Pro (1948, 1949, 1952–1955). During his career, he was one of the NFL's leading receivers. He was named to the NFL 1940s All-Decade Team in 1969 and inducted into the Pro Football Hall of Fame in 1970.