Prince Louis Arthur Charles of Cambridge was born on April 23 - St. George's Day, England's national day - at St Mary's Hospital in central London weighing eight pounds and seven ounces (3.8 kilogrammes).
Lady Laura Meade will Godmother to Prince Louis.
The prince's six godparents were among the guests including the Duke's close friend Guy Pelly, who was once dubbed William and Harry's "court jester" for his wild ways.
According to Kensington Palace, Prince Louis is wearing a handmade replica of the Royal Christening Robe, made by Angela Kelly, Dressmaker to The Queen.
Louis is fifth in the line of succession to the British throne after his grandfather Prince Charles, his father William and his older siblings George and Charlotte.
Prince Louis, the third child of Britain's Prince William and wife Kate, has been christened at a small, private ceremony overseen by close family but without his great-grandmother Queen Elizabeth.
Princess Eugenie is the only one of Queen Elizabeth II's children and grandchildren not to be baptised in the Lily Font; hers was a public christening instead. The original, retired in order to preserve it, was worn for all royal baptisms since 1841.
St James's Palace was built between 1531 to 1536 by King Henry VII and dedicated to Saint James the Less.
But that wasn't evening the best moment of the royal christening.
Our bets are on Princess Charlotte doing the same. (This church has its own significance for the royal family: it was where Charlotte's late grandmother, Princess Diana, was herself baptized.) Also at her christening, Charlotte's five godparents were officially named, including some of her parents' nearest friends and relative.
The couple commissioned the gown in 1841, and used the same fabrics from the Queen's wedding dress the previous year - Spitalfields silk and Honiton lace.