The christening was private, with only senior royals, four members of the Middleton family, the seven godparents and their spouses among the 22 guests.
Prince George, son of the Duke and Duchess of Cambridge, was born in London on 22 July.
The duchess carried her newly christened son out of the chapel after the ceremony, and the guests then left for tea hosted by the Prince of Wales at Clarence House.
The godparents, announced earlier, are Oliver Baker, Emilia Jardine-Paterson, Earl Grosvenor, Jamie Lowther-Pinkerton, Julia Samuel, William van Cutsem and Zara Tindall.
Mrs Tindall, wife of former England rugby player Mike Tindall, is Prince William’s cousin, while the other six godparents are all friends of the royal couple.
Prince George was baptised in a replica of the lace and satin christening gown made for Queen Victoria’s eldest daughter, Victoria, the Princess Royal, in 1841.
The duke and duchess chose two hymns, two lessons and two anthems for the christening.
The hymns were Breathe on Me, Breath of God and Be Thou My Vision.
Lessons from St Luke and St John were read by Pippa Middleton and Prince Harry, and the anthems were Blessed Jesu! Here we Stand and the Lord Bless You and Keep You.
The anthems were sung by the Choir of Her Majesty’s Chapel Royal, which performed at the royal couple’s wedding.
The ceremony took about 45 minutes in total.
After the ceremony, celebrity photographer Jason Bell was expected to take a picture of the Queen and princes Charles, William and George together.
This will echo a 1894 picture from the christening of the future Edward VIII, showing him with his father, grandfather and great-grandmother – George V, Edward VII and Queen Victoria.
The picture is expected to be released on Thursday morning.