After months of speculation, the happy news was announced this afternoon. The Palace said in a statement, "Their Royal Highnesses the Duke and Duchess of Cambridge are very pleased to announce that the Duchess of Cambridge is expecting a baby. The Queen, the Duke of Edinburgh, the Prince of Wales, the Duchess of Cornwall and Prince Harry and members of both families are delighted with the news".
David Cameron also made a statement via twitter. He wrote, "they will make wonderful parents".
A spokesperson said that the Duchess is suffering from hyperemesis gravidarum, severe morning sickness, and has been admitted to King Edward VII Hospital in London. She is expected to stay there for a few days to recover. It is thought that Kate has not yet reached the 12-week stage of her pregnancy.
So now comes the next question: boy or girl?
We'll keep you up to date on all the latest royal baby news. Here's more of the couple below:
Find out more about the news in the video: