It was one of the 85-year-old pontiff's last appearances before withdrawing to assume what Vatican officials described as a cloistered life of prayer and meditation, the Italian news agency ANSA reported.
The pope urged the crowd "to renew firm trust in the Lord" and thanked all the people who "have helped me and been close to me."
"I wish my greetings and my thanks to reach everyone: the heart of a Pope expands to (embrace) the whole world," he said.
The Pope also thanked the crowd for understanding and accepting his decision to resign and allow the selection of a new pope.
"I ask you to remember me before God, and above all to pray for the cardinals, who are called to so important a task," he said.
Benedict's looming departure has triggered a surge of maneuvering among the 117 cardinals who will elect his successor in a conclave beginning next month, The New York Times reported.
Absent from the conclave will be Britain's most senior Roman Catholic cardinal.
On Monday, the Vatican confirmed the resignation of Cardinal Keith O'Brien, the archbishop of Scotland, who was accused of making unwanted sexual advances toward priests years ago.