The longtime lobbyist and former aide to President Lyndon B Johnson suffered a stroke in March and never fully recovered, eventually succumbing to complications at his home in Washington DC.
The Houston-born Valenti developed a passion for film as a boy after he got a job sweeping floors in a local cinema. He earned the Distinguished Flying Cross for flying bombing missions over Italy in the second world war, before returning home to set up an advertising and political consultancy in 1952.
He became a consultant to Johnson and experienced one of the defining moments of his life on Nov 22 1963 when he travelling in the Texas motorcade when President Kennedy was assassinated. Valenti boarded the Air Force One flight back to Washington when Johnson was sworn in as President, before he himself was appointed as the new incumbent's special assistant.
Years of congressional relations and speech editing followed, however by 1966 the lure of Hollywood proved irresistible, and Valenti answered the call from moguls Lew Wasserman and Arthur Krim to take the reins at the MPAA.
As befits a man renowned for his inexhaustible energy and intellectual curiosity, the diminutive Valenti took big strides, abolishing the Hays Code that restricted on-screen sex and violence and orchestrating an overhaul of the ratings system.
'While I believe that every director, studio has the right to make the movies they want to make, everybody else has a right not to watch it,' Valenti told The Associated Press in 2004. 'All we do is give advance cautionary warnings and say this is what we think is in this movie.'
In his later years at the MPAA, Valenti focused his energies on global piracy and emerging technologies. He retired in September 2004 after 38 years in the post, and remained active with a busy schedule of writing, charitable work, and speeches. His memoir This Time, This Place will be published in June.
'Jack was a showman, a gentleman, an orator, and a passionate champion of this country, its movies, and the enduring freedoms that made both so important to this world,' Valenti's successor and serving MPAA chief Dan Glickman said in a statement.
'In a sometimes unreasonable business, Jack Valenti was a giant voice of reason,' said Steven Spielberg. 'He was the greatest ambassador Hollywood has ever known and I will value his wisdom and friendship for all time.'
'Jack was one of a kind,' said Disney president and CEO Robert Iger. 'He was not only an incredible champion for the movie industry, but a man of great intelligence, integrity and humor with an uncanny ability to turn great thoughts into great words. The love he had for his family, his country and the industry was extraordinary. He will be missed by all those who knew him.'
'All of us in the motion picture industry owe a tremendous debt of gratitude to Jack Valenti and mourn his passing,' added Dick Cook, chairman of Walt Disney Studios. 'For nearly four decades, he faithfully and vigorously protected the rights of the film community, and was the most eloquent spokesperson that Hollywood ever could have hoped for. In addition to his role in creating the film rating system, he sought to protect intellectual properties and ensure that new technologies had the proper and necessary safeguards. Jack was a legendary figure whose wisdom and influence benefited Hollywood and the world.'
'I've known Jack for more than 25 years as a colleague, friend and mentor,' said Jean Prewitt, president of IFTA. 'He was the absolute consummate gentleman who loved every facet of our industry and its people - no matter what their role in the business. We'll never forget Jack and his legacy. There will never be anyone like him.'
Valenti is survived by his wife Mary Margaret and his three children, Courtenay, John, and Alexandra.