Susskind was born to a Jewish family of modest means in Manhattan, and grew up in Brookline, Massachusetts. He attended the University of Wisconsin–Madison and then Harvard University, graduating with honors in 1942. He served during World War II and, as communications officer on an attack transport, USS Mellette, saw action at Iwo Jima and Okinawa.
His first job after the war was as a press agent for Warner Brothers. Next he was a talent agent for Century Artists, ultimately ending up in the powerhouse Music Corporation of America's newly minted television programming department, managing Dinah Shore, Jerry Lewis, and others. In New York, Susskind formed Talent Associates, representing creators of material rather than performers. Ultimately, Susskind produced movies, stage plays and television programs.
In 1954, Susskind became producer of the NBC legal drama Justice, based on case files of the Legal Aid Society of New York. His program, Open End, began in 1958 on New York City's commercial independent station WNTA-TV, channel 13, the predecessor to WNET, and was appropriately titled: the program continued until Susskind or his guests were too tired to continue.
In 1961, Open End was constrained to two hours and went into national syndication. The show was retitled The David Susskind Show for its telecast on Sunday night, October 2, 1966. In the 1960s it was the first nationally broadcast television talk show to feature people speaking out against American involvement in the Vietnam War. In the 1970s it was the first nationally broadcast television talk show to feature people speaking out for gay rights. The show continued until its New York outlet cancelled it in 1986, approximately six months before Susskind died.
During his almost three decade run, Susskind covered many controversial topics of the day, such as race relations, transsexualism and the Vietnam War. His interview of Soviet Premier Nikita Khrushchev, which aired in October 1960, during the height of the Cold War, generated national attention. It is one of the very few talk show telecasts from the era that was preserved and can be viewed today.
In 1961, Susskind conducted a series of interviews with former President Harry Truman in Truman's hometown of Independence, Missouri. After picking Truman up at his home to take him to the Truman Presidential Library for the interviews over a number of days, Susskind asked Truman why he hadn't been invited into the home. According to presidential historian Michael Beschloss, Truman flatly told Susskind, "This is Bess's house" and that there had never been nor would there ever be a Jewish guest in there.
Joyce Davidson, with whom Susskind was in a relationship, began working as a co-producer of a television talk show Susskind hosted locally in New York called Hot Line in June 1964. It was a different show from the Open End talk show. Hot Line was the first television show to use the recently invented ten-second broadcast delay to amplify viewer phone calls on the air. Davidson screened viewer phone calls. She also made the first approach to some of the people who appeared as guests on Hot Line, including Malcolm X, whom she invited for Hot Line immediately after he gave a speech at The Town Hall.
Notwithstanding a perhaps courageous willingness to present challenging political issues of his times to audiences, a thorough analysis of his editorial perspective would be incomplete without considering recently unearthed film footage of Susskind's 1968 appearance on The Eamonn Andrews Show, when he excoriated Muhammad Ali with withering criticism for refusing to be conscripted into the U.S. military for the Vietnam War.
Susskind was also a noted producer, with scores of movies, plays, and TV programs to his credit. His legacy is that of a producer of intelligent material at a time when TV had left its golden years behind and had firmly planted its feet in programming which had wide appeal, whether or not it was worth watching. Among other projects, he produced television adaptations of Beyond This Place (1957), The Bridge of San Luis Rey (1958), The Moon and Sixpence (1960), Ages of Man (1966), Death of a Salesman (also 1966), Look Homeward, Angel (1972), The Glass Menagerie (1973), and Caesar and Cleopatra (1976); the television films Truman at Potsdam (1976), Eleanor and Franklin (1976), and Eleanor and Franklin: The White House Years (1977); and the feature films A Raisin in the Sun (1961), Loving Couples (1980). In 1964, he produced Craig Stevens's acclaimed CBS drama Mr. Broadway, which left the air after thirteen episodes. He also produced and owned all the rights to the 1961 fourteen-episode macabre CBS TV series – Way Out. His production company, Talent Associates, also produced Get Smart.
Susskind was married twice. Both of his marriages ended in divorce. In 1939, he married Phyllis Briskin; they had three children: Diana Susskind Laptook, Pamela Susskind Schaenen, and Andrew Susskind. They divorced in 1966. In the same year he married Joyce Davidson, who had two daughters from a prior marriage, Connie and Shelley. They had a daughter, Samantha Maria Susskind Mannion. They divorced in 1986.
Susskind was first cousin to noted television writer and producer Norman Lear. He is survived by his sister, Dorothy Barron, and brother, Murray.
In 1987 at the age of 66, Susskind suffered a fatal heart attack in New York City. He was interred at Westchester Hills Cemetery in Hastings-on-Hudson, New York.
In 1988, Susskind was inducted into the Television Hall of Fame.