The UK was among 212 nations registered to take part, with major prayer and cathedral events taking place across England, Scotland, Wales and Northern Ireland under the common theme of "Your Kingdom come ... on Earth as in Heaven".
In London, thousands of Christians gathered at Millwall football stadium in central London to pray for God's love and Holy Spirit to fall upon London, particularly communities blighted by gun and knife crime.
The message on the day was overwhelmingly one of hope and unity. "When the church unites in prayer there is no stopping it," said Jonathan Oloyede, senior Associate Pastor of Glory House and visionary of Global Day of Prayer London. "Prayer changes things," he added.
Last week, Prime Minister Gordon Brown hosted a reception at 10 Downing Street in honour of Global Day of Prayer in which he praised the contribution of faith groups to the United Kingdom.
"When our government leaders begin to value what the church is doing in this country, we are in for revival," continued Pastor Oloyede.
Newly elected London Mayor Boris Johnson took to the stage to ask that Christians pray for young victims of gun and knife attacks as well as their families. A total of thirteen young people have been shot or stabbed to death in the capital so far this year.
He paid tribute to devout Catholic teenager Jimmy Mizen, who was murdered on Saturday in an unprovoked attack in a south-east London bakery the day after his 16th birthday, and Borough teenager Lyle Tulloch, who was murdered a week ago.
