The frail Pope, 85, arrived in his Pope mobile to cheers, thanking everyone for understanding his decision to leave his position due to his age and health, making him the first modern-era Pope to step down rather than serve for life, as is tradition in the Catholic church.
"To love the church also means having the courage to take difficult decisions," he said in his address.
The pontiff's resignation takes effect Thursday. He will keep the name Benedict XVI and become the Roman pontiff emeritus or pope emeritus, the Vatican announced Tuesday.
Later he will depart for Castel Gandolfo, the summer residence of popes, and will live there until restorations are complete on the Vatican convent, which will become his permanent home.
The former Cardinal Joseph Ratzinger became Pope in 2005 after the death of Pope John Paul II. He Tweeted a message Wednesday honoring his deep faith.
"If only everyone could experience the joy of being Christian, being loved by God who gave his Son for us!"