Born in Drexel Hill, Pennsylvania, Hack attended the Lynnewood School, and Haverford High School, on the Main Line in suburban Philadelphia. He later attended Pennsylvania State University and holds a Master’s Degree in Environmental Design.

Hack moved to Los Angeles where he was hired by TV Guide magazine as its West Coast national programming editor. By the early 80s, Hack began writing the TeleVisions column for the daily entertainment trade paper, The Hollywood Reporter. During the next decade, Hack was instrumental in propelling the paper into a dominant position over rival Variety, and often appeared on The Tonight Show and Today reporting on Hollywood.

During the same period, he was a frequent guest on Oprah Winfrey, Good Morning America, Larry King Live, Charlie Rose, Tomorrow, Entertainment Tonight, and Access Hollywood.

In 1990, Hack left The Hollywood Reporter to become Vice President of Creative Affairs at Dove Audio and Entertainment, a production company that specialized in miniseries and books-on-tape. While at Dove, Hack adapted Sidney Sheldon’s The Sands of Time, Memories of Midnight, and The Stars Shine Down as mini-series, which he also produced, and wrote his first book, Next to Hughes with Robert Maheu.

Since leaving Dove, Hack moved to a horse ranch in Maui, where he stabled polo ponies, and established a home on the Intracoastal in Florida.

His bestseller Hughes: The Private Diaries, Memos and Letters was released on September 11, 2001. Hack was being interviewed live on the Today show by Matt Lauer when the first plane crashed into the World Trade Center.

His subsequent book, PuppetMaster: The Secret Life of J. Edgar Hoover is being made into a feature film by HBO Films.

It is sometimes stated that Hack's book Hughes served as the basis for Martin Scorsese's 2004 film about Howard Hughes, The Aviator.

However, two competing films about Hughes were in development at the same time. The other film was to have been directed by Christopher Nolan, with star Jim Carrey and financing from Castle Rock. Its script was going to be based on Hack's biography. That film was never produced.