George was christened by Archbishop of Canterbury Justin Welby during a private ceremony at the Chapel Royal at St. James's Palace.
The momentous occasion included four generations of royals: the presence of Britain's 87-year-old monarch and three of its future kings. It was also the first time the public had seen George since he was born on July 22.
Prince George wore a replica of an intricate lace and satin christening gown made for Queen Victoria's eldest daughter. The original was first used in 1841 but was retired in 2004 after it was deemed too fragile by the queen.
He arrived at the chapel in his father's arms with his mother by their side, and appeared to wave at his great-grandmother, Queen Elizabeth II, although it was really a case of William moving his son's hand up and down.
Kate wore a cream-colored Alexander McQueen dress and hat by miliner Jane Taylor with her long hair brushed to the side. William wore his customary dark suit and tie as he proudly carried their child.
Queen Elizabeth II and her husband Prince Philip attended the christening Wednesday, along with Prince Charles, his wife Camilla, Prince Harry and other royals.
Kate's parents Michael and Carole Middleton and her sister Pippa and brother James were also in attendance.
Pippa Middleton read from the Gospel of St. Luke and Prince Harry read from the Gospel of St. John. The two hymns were "Breathe on Me, Breath of God" and "Be Thou My Vision."
The 16th century chapel ceremony broke royal tradition but held great significance. The location is where the late Princess Diana's coffin was laid for her family to pay their last respects in private before her 1997 funeral.
Prince William and his wife Kate asked seven people to be godparents to the 3-month-old future monarch.
The godparents include close friends from their university days, a friend of William's late mother, Princess Diana, a childhood chum of William, and a school friend of Kate's.
They are: Oliver Baker, a friend from St. Andrews University; Emilia Jardine-Paterson, who went to the exclusive Marlborough College with Kate; Earl Grosvenor, who is the son of the Duke of Westminster; Jamie Lowther-Pinkerton, a former private secretary to the couple; Julia Samuel, described as a close friend of the late Princess Diana; Zara Phillips, who is William's cousin, and William van Cutsem, a childhood friend of William.
Charles and Camilla hosted a private tea party at their Clarence House residence following the ceremony. William and Kate served a tier of their royal wedding cake which they had saved since the joyous event in 2011.
William and Kate hired photographer Jason Bell to take official pictures of the events, which are expected to include a historic multi-generational photograph of the queen with three future monarchs: her son Charles, her grandson William and her great-grandson George.
The official photographs are expected to be released to the public Thursday.
The Associated Press contributed to this report.