Pope Benedict XVI delivered his final Angelus blessing to a crowd of around 100,000 at St Peter's Square in Rome on Sunday.
The 85-year-old said he would continue to serve the Church after stepping down on Thursday.
Crowds cheered and waved banners thanking the Pope as he delivered the blessing from a window overlooking the square.
The Pope said he had been "called" to a life of reflection and prayer.
"But this doesn't mean abandoning the Church", he said.
The Pope said he would continue to serve the Church "with the same dedication and the same love which I have tried to do so until now, but in a way more suitable to my age and to my strength".
His last public appearance as Pope will be on Wednesday when throngs of people are expected to pack the square again for his general audience.
The Vatican has dismissed rumours that the Pope's resignation was linked to an alleged network of gay priests.
A conclave of 116 cardinals will meet in the coming weeks to elect the Pope's successor.