At her side during the delivery was husband Prince William, Duke of Cambridge, 31.
Prior to the delivery, the couple stayed mum about the sex of their baby, however, during a public appearance in March, Middleton accidentally let it slip that she might be expecting a daughter.
Someone had gifted Middleton with a teddy bear at the event, and one woman claimed she heard the duchess respond, saying, "Thank you, I will take that for my d..."
Earlier this month, Queen Elizabeth decreed that the royal baby will be a prince, making him HRH Prince of Cambridge. He will be third in line to the British throne.
News initially broke about the Duke and Duchess' pregnancy in January when Kate was admitted to a London hospital to be treated for hyperemesis gravidarum, a more severe form of the nausea and vomiting that normally accompanies the early stages of pregnancy. She was just twelve weeks along at the time.
The new parents' bouncing baby boy comes after two years of marriage. Will and Kate tied the knot in a lavish ceremony at Westminster Abbey April 29, 2011, broadcast live around the world.
