Orang tua Tomlinson, Troy Austin dan Johannah Poulston, berpisah ketika ia masih balita. Ia terasing dari ayahnya.<ref>{{cite web|url=http://hollywoodlife.com/2013/03/25/louis-tomlinson-dad-interview-sunday-mirror-rift-reconcile/|title=Louis Tomlinson's estranged father hopes to reunite and heal rift|work=Hollywood Life|date=22 March 2014}}</ref>Ia memiliki empat adik tiri perempuan dari pernikahan kedua ibunya dengan Mark Tomlinson: Charlotte "Lottie", Félicité "Fizzy", dan si kembar identik Daisy dan Phoebe, yang memiliki peran sebagai bayi di serial televisi ''Fat Friends'' bersama abang mereka. Mark dan Johannah bercerai ketika Louis berkompetisi di ''The X Factor''. Tomlinson mempunyai adik tiri perempuan yang lain, Georgia, dari pernikahan kedua ayahnya.<ref>{{cite news|title=Louis Tomlinson: One Direction star's secret family hope to heal rift|url=http://www.mirror.co.uk/3am/celebrity-news/louis-tomlinson-one-direction-stars-1781419|date=24 March 2013|work=[[Daily Mirror|The Mirror]]|publisher=[[Trinity Mirror]]|accessdate=13 February 2014}}</ref>Diumumkan pada bulan Oktober 2013 ibunya Poulston mengandung anak kembar dari tunangannya, Daniel Deakin. Ia melahirkan sepasang anak kembar fraternal, Ernest dan Doris, pada 12 Februari 2014.<ref>{{cite web|url=http://www.dailymail.co.uk/tvshowbiz/article-2557409/One-Direction-star-Louis-Tomlinson-celebrating-mother-gave-birth-twins.html|title=One Direction's Louis Tomlinson celebrates mother giving birth to twins - Daily Mail Online|work=Mail Online|accessdate=12 December 2014}}</ref> Poulston menikahi Deakin pada tanggal 20 Juli 2014.<ref>{{cite web|url=http://www.mirror.co.uk/3am/celebrity-news/watch-one-direction-arrive-smartest-3888149|title=Watch One Direction arrive in their smartest suits and shades for Louis Tomlinson's mum's lavish wedding|author=Rebecca Pocklington|date=20 July 2014|work=mirror|accessdate=12 December 2014}}</ref>
Tomlinson berpacaran dengan mahasiswa Eleanor Calder selama hampir empat tahun, tapitetapi keduanya putus Maret 2015.<ref>{{cite web|url=http://www.dailymail.co.uk/tvshowbiz/article-3006032/One-Direction-s-Louis-Tomlinson-splits-long-term-girlfriend-Eleanor-Calder-pictures-emerge-kissing-mystery-woman-night-pool-party-Thailand.html|title=One Direction's Louis Tomlinson splits from girlfriend Eleanor Calder|work=Mail Online|date=22 March 2015}}</ref>Pada bulan Juli 2015 dilaporkan bahwa Tomlinson akan mempunyai bayi dengan stylist Amerika, Briana Jungwirth, yang berbasis di Los Angeles, dan pada awal Agustus 2015, pada ''[[Good Morning America]]'', ia mengonfirmasi laporan tersebut.<ref>{{cite news|url=http://www.dailymail.co.uk/tvshowbiz/article-3190563/Louis-Tomlinson-s-baby-mama-Briana-Jungwirth-steps-revealing-burgeoning-bump-time.html|title=Big debut! Louis Tomlinson's baby mama Briana Jungwirth steps out revealing her burgeoning bump for the first time|work=Daily Mail|date=8 August 2015|accessdate=11 August 2015}}</ref><ref>{{cite web|url=http://www.nydailynews.com/entertainment/tv/louis-tomlinson-confirms-baby-news-gma-article-1.2314057|title=Louis Tomlinson confirms baby news on ‘Good Morning America,’ says ‘it’s a very exciting time’|work=NY Daily News|date=4 August 2015}}</ref><ref>{{cite web|url=http://www.cambio.com/2015/08/04/louis-tomlinson-confirms-hes-going-baby-daddy-gma-interview-video/|title=Louis Tomlinson Confirms He's Going to Be a Dad During 'GMA' Interview|author=Wendy Michaels|work=Cambio}}</ref><ref>{{cite web|url=http://www.vanityfair.com/hollywood/2015/08/louis-tomlinson-pregnancy-good-morning-america|title=One Direction’s Louis Tomlinson Publicly Acknowledges That He’s Going - Vanity Fair|author=Richard Lawson|work=Vanity Fair}}</ref><ref>{{cite web|url=http://www.usmagazine.com/celebrity-news/news/louis-tomlinson-breaks-silence-on-baby-news-its-a-very-exciting-time-201548|title=Louis Tomlinson Breaks Silence on Baby News: It's a Very Exciting Time - Us Weekly|date=4 August 2015|work=usmagazine.com}}</ref><ref>{{cite web|url=http://www.capitalfm.com/artists/one-direction/louis-tomlinson/news/father-expecting-baby-briana-jungwirth/|title="I'm Buzzing": Louis Tomlinson Finally CONFIRMS He's Having A Baby With Briana Jungwirth|date=4 August 2015|work=Capital}}</ref><ref>{{cite av media|url=https://www.youtube.com/watch?v=mrjueYEjTw0|title=One Direction 1D - FULL INTERVIEW - Louis Tomlinson Talks Fatherhood on GMA - Good Morning America|date=4 August 2015|work=YouTube}}</ref> Putra mereka, bernama Freddie Reign,<ref>{{Cite web|title = Louis Tomlinson on Instagram: “Meet my little lad, Freddie 👶”|url = https://www.instagram.com/p/BBEYEDPL4Z2/|website = Instagram|accessdate = 28 January 2016}}</ref><ref>{{Cite web|title = Briana Jungwirth on Instagram: “1/21/16. Freddie Reign. Love of my life💙”|url =https://www.instagram.com/p/BBEc9qxgWtt/|website = Instagram|accessdate = 28 January 2016}}</ref> lahir pada tanggal 21 Januari 2016.<ref>{{cite web|url=https://twitter.com/Louis_Tomlinson/status/690859667224928256?ref_src=twsrc%5Etfw|title=Louis Tomlinson on Twitter: “I'm pleased to say my baby son was born yesterday :) 👶 He is healthy and pretty amazing :) I'm very happy!!”|website=Twitter|date=23 January 2016|accessdate=28 January 2016}}</ref><ref>{{cite web|url=http://www.bbc.co.uk/newsbeat/article/35391277/louis-tomlinson-confirms-that-he-has-become-a-dad|title= Louis Tomlinson confirms that he has become a dad|work=Newsbeat|date=23 January 2016|accessdate=28 January 2016}}</ref>
Louis menjadi juri tamu di ajang ''American Got's Talents''. Dia menjadi juri tamu atau ''judge cuts'' karena undangan Simon Cowell.
