The atmosphere was festival-like in spite of the protest waged at one corner of the park by demonstrators angry over the Catholic Church's position on issues like homosexuality and abortion, and its handling of paedophile priests.
As the Pope's journey through London in his Popemobile played out on the big screens, thousands of ecstatic youths waved banners and flags and chanted "We love you Benedict".
In a rather candid sermon, the Pope told the crowds they were "suffering" for their faith as he recalled the martyr of Catholics at Tyburn.
"In our own time, the price to be paid for fidelity to the Gospel is no longer being hanged, drawn and quartered but it often involves being dismissed out of hand, ridiculed or parodied," he said.
"And yet, the Church cannot withdraw from the task of proclaiming Christ and his Gospel as saving truth, the source of our ultimate happiness individuals and as the foundation of a just and humane society."
The Pope went on to say that a passion for the truth, intellectual honesty and genuine conversation would be "costly", as he urged believers to close the gap between the beliefs and how they lived out their daily lives.
"Truth is passed on not merely by formal teaching, important as that is, but also by the witness of lives lived in integrity, fidelity and holiness," he said.
The vigil was at times jovial and party-like, with dance and drama, and at other times solemn, with traditional hymns.
Many pilgrims had been in the park arena since lunchtime to see the Pope, with many making a day of it by bringing their seats and picnics.
The vigil was held in preparation of tomorrow's beatification of John Henry Newman, who converted from Anglicanism to Roman Catholicism. Tens of thousands are expected to fill Birmingham's Crofton Park for the occasion on the last day of the Pope's state visit to Britain.