The Arsenal footballer posted the adorable photo on his official Facebook account yesterday (12 April).
Alongside the black and white snap of the sleepy newborn, proud dad Theo wrote: "Welcome Finley James Walcott to the world! X."
From the looks of it, Finley is already the spitting image of his famous daddy.
After seeing the picture, fans messaged their congratulations.
One fan joked "new property of arsenal", while another spoke for many by writing: "That is the cutest baby in the world."
Theo's wife Melanie Slade gave birth to their first child just days ago.
He announced the happy news on Thursday night (10 April), telling fans they were overjoyed to welcome Finley to their family.
The currently injured England star Theo wrote: "So over the moon to announce the birth of our baby boy Finley born this morning.... It's amazing to be mummy & daddy! Love him so much."
He and sports physiotherapist Melanie announced the pregnancy just before Christmas, saying: "Me & Mel are happy to confirm we are expecting our first child, which is due early next summer. We are both very excited at such happy news just a few months after getting married.
"We are really looking forward to becoming parents."
The childhood sweethearts became engaged on New Year's Eve in 2011, after Theo popped the question at their Hertfordshire home.
Do you think little Finley looks like his footballer daddy, Theo Walcott? Tell us below!
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