The three-month-old, who will one day be king, appeared to be on his best behaviour as he was carried by his mother the Duchess of Cambridge out of the service in the historic Chapel Royal at St James's Palace.
George had arrived for his christening in the arms of his father, the Duke of Cambridge, and gurgled happily when his great grandparents The Queen and The Duke of Edinburgh arrived. William told everyone: "He's all ready", adding: "So far so good."
Prince George will have seven godparents, including Zara Phillips and six of his parents' close friends.
The day was clearly a happy event for the royals and Kate's family - parents Carole and Michael Middleton and siblings Pippa and James - with a Kensington Palace spokesman saying after the service: "It has been a tremendously joyful occasion for everyone involved."
Archbishop of Canterbury the Most Rev Justin Welby said during the service that the parents and godparents of George have a "simple task" to "make sure he knows who this Jesus is".
He told the guests that as a Christian George "is to share the life of Christ which is in him, regardless of whom he meets, their faith or nature or habits, so that others find life". That sharing may be in words, or generous actions -most likely both - but it will be both very costly and infinitely rewarding."
Prince Harry and Pippa Middleton gave readings at the christening while the two hymns were Breathe on Me, Breath of God and Be Thou My Vision.
The day ended with the guests enjoying afternoon tea at Clarence House hosted by Charles and Camilla.