The younger sister of the Duchess of Cambridge, and her husband - who is brother to Made In Chelsea star Spencer Matthews - welcomed their little one into the world at the famous Lindo Wing at St Mary's Hospital in London. A spokesperson for the columnist and her partner told HELLO! News, "The Duke and Duchess of Cambridge are thrilled for Pippa and James".
Both mother and son are said to be "doing well" according to a statement released on behalf of the Matthews family.
Pippa had been keeping her fans up to date about her pregnancy progress through her fitness column for Waitrose.
The news comes just days after Middleton and Matthews, who Wednesday in May 2017, were photographed attending the October 12 wedding of Princess Eugenie and Jack Brooksbank.
Trump hails 'truly attractive bride Princess Eugenie but gets wedding date wrong
After their afternoon reception in Windsor Castle, Jack drove Eugenie away in a silver DB10 Aston Martin sports vehicle . Basically, Princess Eugenie and the rest of the royal fam threw the chicest carnival ever.
Pippa, who was wearing a long blue coat, white shoes and sunglasses, was smiling as she entered the £7,500-a-night unit.
Pippa and James married in May 2017 in the village of Englefield, near Reading and they announced their baby news earlier this year.
Ahead of Prince Louis' birth, Katherine Filkins told HELLO! what her experience giving birth in the exclusive wing was like.
A standard room at the Lindo Wing costs nearly $11,000 with deluxe rooms starting at $11,500. Reality is finally kicking in. There was a wine list, you could have had champagne if you wanted.