St Patrick is the patron Saint of Ireland and the 17 March marks the traditional day of celebration.
Thousands of people lined the streets of Dublin and New York City for the annual parades.
Prime Minister of Ireland, Leo Varadkar was in New York for the celebrations, just days after presenting US President Donald Trump with a bowl of shamrocks at the White House.
Star Wars actor Mark Hamill and his wife Marilou York braved the cold temperates to celebrate the occasion at the St Patrick’s Day parade on the streets of Dublin.
Many famous landmarks around the world turned green in honour of Ireland’s patron saint.
Green lights illuminated the Chain Bridge in Budapest, Hungary, the Cibeles Fountain in downtown Madrid.
One US city went one step further and turned the Chicago River bright green.
The weekend also saw a heavily pregnant Kate Middleton brave the snow and ice in Hounslow, west London to join husband Prince William, Colonel of the Irish Guards, for the annual St Patrick’s Day Parade.
The Duchess of Cambridge, who is due to give birth in April, visited the 1st Battalion of Irish Guards at the Household Cavalry Barracks to present traditional shamrocks to the officers.
Look through this gallery to see how the world celebrated St Patrick’s Day.