Freed had wanted to be a painter, but began taking photographs in the Netherlands and discovered a new passion. He travelled in Europe and Africa before returning to the United States where he attended The New School and studied with Alexey Brodovitch, the art director of Harper's Bazaar. In 1958 he moved to Amsterdam to photograph its Jewish community. Through the 1960s he continued to work as a freelance photojournalist, travelling widely. He documented the Civil Rights Movement in America (1964–1965), the Yom Kippur War in 1973, and the New York City police department (1972–1979).
His career blossomed during the American civil rights movement when he travelled the country with Martin Luther King Jr. in his celebrated march across the U.S. from Alabama to Washington.[clarification needed] This journey gave him the opportunity to produce the book Black in White America (1968), which brought considerable attention. His work on New York City law enforcement also led to a book, Police Work (1980).
Early in Freed's career, Edward Steichen purchased three photographs from him for the Museum of Modern Art collection. In 1967, Cornell Capa selected Freed as one of five photographers to participate in his Concerned Photography exhibition. Freed joined Magnum Photos in 1972. He contributed to publications including Der Spiegel, Die Zeit, Fortune, Libération, Life, Look, Paris-Match, Stern, and The Sunday Times Magazine of London.
In later years, Freed continued photographing in Italy, Turkey, Germany, Lebanon and the U.S. He also shot four films for Japanese, Dutch and Belgian television.