Benenson died on Friday evening in the John Radcliffe Hospital in Oxford, west of London.
Benenson started the organisation in 1961 after having read an article about two students who were arrested and imprisoned for drinking a toast to liberty in a café in Lisbon, Portugal, then under a dictatorship.
"Peter Benenson's life was a courageous testament to his visionary commitment to fight injustice around the world," said Irene Khan, the organization's secretary-general.
"He brought light into the darkness of prisons, the horror of torture chambers and the tragedy of death camps around the world."
In the first few years of Amnesty's existence, the London-born Benenson supplied much of the funding for the movement, went on research missions and was involved in all aspects of the organisation's affairs.
At its 25th anniversary, he lit what has become Amnesty's symbol - a candle entwined in barbed wire - and said that it burned "for all those whom we failed to rescue from prison, who were shot on the way to prison, who were tortured, who were kidnapped, who disappeared. This is what the candle is for".
Now in its 44th year, Amnesty International has become the world's largest human rights group with more than 1.8 million members and committed supporters worldwide.