"After 3 baftas and one Emmy... finally we have won an Oscar, please welcome Oscar James Ramsay, who touched down at 12:58 today for some lunch ! Xxx"
Posting a series of photos, young Oscar is cradled in Tana's arms, as Gordon smiles on.
Gordon and Tana announced they were expecting back in January.
"Exciting news," they shared on Instagram.
"Happy new year from all the Ramsay's."
Oscar joins his siblings Megan, 21, Matilda, 17, and fraternal twins Jack and Holly, 19.
His arrival follows the family's heartbreak when Tana suffered a miscarriage less than two years ago.
At the time, the pair thanked everyone for their support.
"We're together healing as a family, but we want to thank everyone again for all your amazing support and well wishes," Gordon wrote in his post.
"I'd especially like to send a big thank you to the amazing team at Portland Hospital for everything they've done. Gx."