Louis, whose son was born on 22nd January, tweeted an intimate photograph of himself and his baby boy with former girlfriend Briana Jungwirth, 24.
The 24-year-old X Factor star also revealed that the couple, who are no longer together, have chosen the traditional name Freddie rather than Sydney Rain - which was speculated earlier in the week when it started trending online.
Louis captioned the candid snap; 'Meet my little lad, Freddie.'
Meet my little lad, Freddie ðŸ‘¶ pic.twitter.com/nec7OqwuQR— Louis Tomlinson (@Louis_Tomlinson) January 28, 2016
Adding only minutes later – 'Freddie Tommo' – indicating that his son will take his surname Tomlinson rather than Jungwirth.
Freddie Tommo— Louis Tomlinson (@Louis_Tomlinson) January 28, 2016
American stylist Briana took to her own social media platform to add that the tot's middle name will be Reign.
Freddie is an abbreviation of the name Frederick and means 'peace ruler' while his middle name, Reign, suggests a highly-born child.
Reign has been trending in celebrity circles recently, as it is also the name of Kourtney Kardashian and Scott Disick's youngest son.
Louis is the latest star to share some very exciting celebrity baby news this week!
The family will be based in Calabasas, Los-Angeles, where other Hollywood celebrities such as the Kardashians live.
Louis will be renting a three-bedroom home for Briana and Freddie to live in together and The Sun newspaper has claimed that Louis will pay up to £2,100,000 in child support.
The Doncaster-born star, who has been part of the boy-band since 2010, confirmed the birth of his child via Twitter last Friday, saying; 'I'm pleased to say my baby son was born yesterday He is healthy and pretty amazing I'm very happy!'
I'm pleased to say my baby son was born yesterday :) ðŸ‘¶ He is healthy and pretty amazing :) I'm very happy!!— Louis Tomlinson (@Louis_Tomlinson) January 23, 2016
Messages of support from fans have been pouring in from around the world, offering congratulations and well wishes for the proud father.
Some eagle-eyed fans even noticed that, despite the ongoing feud between Zayn Malik and his former bandmates, Zayn had liked the picture of Louis and his new son.
Louis and his bandmates
The news that Louis was going to become a father first broke last July while he was travelling with the On The Road Again world tour.
Louis is now dating Danielle Campbell, a Disney television star.