The TOWIE star announced the news with an Instagram post on Wednesday 30 December.
The new mum captioned the image: "Welcome to the world our beautiful baby boy 29.12.15"
Faiers and her boyfriend Paul Knightley announced they were expecting their first child together in August.
The couple have only just found out the gender of their baby, as they decided to wait until the birth to find out if they were having a boy or a girl.
Faiers previously told The Mirror: "We want the sex [of the baby] to be a surprise.
"I thought if we're both not desperate to find out let's keep it a surprise because it would be so lovely."
The family have a lot of celebrating to do as Faiers gave birth just two days before her own birthday on New Year's Eve.
Faier's older sister Billie, who has a one-year-old daughter Nelly, shared the photo of the newborn's hand alongside the message:
"I am the proudest sister and auntie in the world @samanthafaiers1 and Paul ... I cannot describe my love for my beautiful nephew ... I love you all so much and I can't wait for all the wonderful time we are going to spend together with him and Nelly ..."
Congratulations to the couple!