Among the pilgrims was the Papal Nuncio, Archbishop Charles Brown (52) who was greeted by thousands as he made his way up the mountain to celebrate mass at the summit at 9.30am.
This was the first time Archbishop Brown had climbed Croagh Patrick.
Speaking during his short Mass, the Papal Nuncio said the climb -- which he did in a sturdy pair of hiking boots while carrying a wooden stick -- was like a pathway to life.
The American archbishop spent almost five hours on the mountain, hearing confessions and chatting with pilgrims. He was so impressed by the event that he hopes to complete it again in the future.
Archbishop Brown was accompanied by the Archbishop of Tuam, Galway, Dr Michael Neary.
Fr Charles McDonnell, administrator of Westport parish of Mayo, also climbed the mountain.
This pilgrimage ended a busy week for the nuncio who had been involved in ordinations in Cork last Sunday.
In his homily at the summit, Archbishop Neary said he hoped the legacy of the International Eucharistic Congress would be to make people more aware of the faith that still existed around the country.
"There is so much good here that has been swallowed up in criticism. There is still a vibrant faith expressed by the many people who trek to daily Mass, those who go out to care for the poor and all those who direct their energies to deprived children and the forgotten elderly," he said.
The pilgrimage, which has been carried out uninterrupted for more than 1,500 years, saw many leave their shoes at home, while others sported their county colours in the hope of some divine intervention.
John Dunleavy and his five-year-old daughter Sorcha took part in the pilgrimage.
This was Sorcha's first climb but she will have a long way to go if she plans to beat her father's record. Mr Dunleavy has made the pilgrimage over 30 times.
Diarmuid MacConville from Dublin made the pilgrimage in his bare feet. But his decision wasn't religiously motivated, he's a fan of barefoot running.
"I read 'Born to Run' by Christopher McDougall and it inspired me. It wasn't very tough. I just took it easy. I've been promised a foot massage when I get home," he added.
Thomas Halloran (13) from Cross in Co Mayo was a minor casualty of the climb. The teen had been doing great until a slip on the way down left him with a bloody knee.
He and his family do the climb each year and Thomas insisted the slight injury wouldn't be putting him off in future.
"Coming down I slipped on the gravel and fell. It's not so bad," he said.
His father Tommy Halloran has been doing the climb each year for the past 25 years. He and his wife Concepta have taken each of their children on the climb from the age of seven on.
This year was the first time for Rebecca (7) who was eager to come back again.
Despite the good weather, the numbers taking part in the climb were lower than in previous years. However, the sight of thousands walking up the mountain was still impressive enough for some visitors.
Matthias Thurmann (23) from Germany was left speechless by the sight of 12,000 people making their way up the mountain.
"It's kind of insane that there really would be thousands of people from all over the world all coming here just to climb this mountain," he said.