The One Direction singer shared a tender image cradling his first child, who was born to former flame Briana Jungwirth last week, and also revealed the name - Freddie Reign.
Gazing down lovingly at his newborn, Louis wrote alongside the image: "Meet my little lad, Freddie" and later thanked fans for their support with a tweet, saying: "Thank you so much for all the nice messages."
How adorable is that? Louis also revealed Freddie will take his surname, Tomlinson, simply writing: "Freddie Tommo" in a Tweet.
Meanwhile, proud new mum Briana also shared a heartwarming photo of herself in hospital shortly after giving birth to Freddie, and revealed his middle name is Reign. So those original baby name rumours weren't too far off then!
Kissing the top of her baby's head while he slept soundly, Briana captioned the image: "1/21/16. Freddie Reign. Love of my life."
Louis first announced the arrival of Freddie on Saturday 23 January, telling his Twitter followers: "I'm pleased to say my baby son was born yesterday :) He is healthy and pretty amazing :) I'm very happy!!"
It's believed that Louis was by Briana's side as she gave birth to the star's first child, as he's currently spending time in California to be close to the new mum and baby.
Briana and Louis went on a series of dates in May 2015, shortly after he split up from his long-term girlfriend Eleanor Calder.
He confirmed that he was going to be a dad during a chat with Good Morning America last August, telling fans he was "buzzing" to become a dad.
It certainly looks like he's loving his new role, right?
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