Niall James Horan was born on 13 September 1993 in Mullingar, Westmeath, Ireland. He has an older brother, Greg Horan. His parents, Bobby Horan and Maura Gallagher, divorced when he was five years old, so he and his brother, Greg, lived with their mother for a year. After spending a year apart from their father, they later decided to move in with him. He had asthma as a child. He attended St. Kenny’s National School, a primary school, and Coláiste Mhuire, a Catholic boys school, which are both located in Mullingar.

In 2010, at sixteen years old, Horan auditioned for the seventh series of The X Factor in Dublin. He sang “So Sick” and received mixed comments from the judges. Louis Walsh was in his favour, but Cheryl Cole and guest judge Katy Perry felt that he needed some time to grow. Simon Cowell voted to let him through, Cole said no, Walsh said yes, and Perry decided to vote yes. Horan was then put through to bootcamp.

Following The X Factor, One Direction was signed by Cowell to a reported £2 million Syco record contract. They began recording their debut album in Los Angeles in January 2011. That February, a book licensed by One Direction, One Direction: Forever Young (Our Official X Factor Story), was released and topped The Sunday Times’ Best Seller list. That same month, the band and other contestants from the series participated in The X Factor Live Tour. During the tour, the group performed for 500,000 people throughout the UK. After the tour concluded in April, the group continued working on their debut album. Recording took place in Stockholm, London, and Los Angeles, as One Direction worked with producers such as Carl Falk, Savan Kotecha, Steve Mac, and Rami Yacoub.

One Direction’s debut single, “What Makes You Beautiful”, was released in September 2011. A global and commercial success, the song reached number one in several countries. Subsequent singles, “Gotta Be You”, “One Thing”, and “More than This”, had also received success, with the first two becoming top ten hits in the UK. In November of that year, the group’s debut album “Up All Night” was released in Ireland and the UK, reaching number one and number two on the charts, respectively. The album was released internationally in March 2012, and One Direction became the first UK group to have their debut album reach number one in the United States. To promote the album, they embarked on their first headlining concert tour, the Up All Night Tour. Originally intended with shows taking place only in Europe, additional dates in North America and Australia were added due to extreme demand. The tour was a commercial success; tickets sold out in minutes, and the tour was met with positive reviews from critics who applauded their singing abilities and stage presence. In May 2012, the band released the tour’s DVD, Up All Night: The Live Tour. That same month, One Direction’s first book to be licensed in America, Dare to Dream: Life as One Direction, was published and topped The New York Times Best Seller list. In September 2012, the group released “Live While We’re Young”, the lead single from their upcoming second album. The album’s second single, “Little Things,” spawned the band’s second number one single in the UK. In November 2012, Take Me Home, One Direction’s sophomore album, was released. It reached number one in over 35 countries, and, after reaching number one on the Billboard 200, the group became the first boy band in US chart history to record two number-one albums in the same calendar year alongside becoming the first group since 2008 to record two number-one albums in the same year. To support the album, they embarked on their second headlining tour, the Take Me Home Tour, playing over 120 shows over four continents. In August 2013, One Direction: This Is Us, a 3-D documentary concert film was released and was a box office success, grossing over $68.5 million. One Direction’s third book, One Direction: Where We Are: Our Band, Our Story: 100% Official, was released that same month.

The band’s third studio album, Midnight Memories, was released on 25 November 2013. It was the best-selling album worldwide in 2013 with 4 million copies sold globally. “Best Song Ever”, the album’s lead single, is One Direction’s highest charting single in the US to date. Following the album’s released, the group embarked on the Where We Are Tour. The band’s first all-stadium tour, tickets sold out in minutes, and more shows were added due to “overwhelming demand.” The band averaged 49,848 fans per show. The tour grossed over $290 million and was the highest-grossing tour of 2014, the 15th highest-grossing concert tour of all time, and is still the highest-grossing tour of all time by a vocal group. In September 2014, One Direction’s fourth book, One Direction: Who We Are: Our Official Autobiography was released. The group’s second concert film, One Direction: Where We Are – The Concert Film, was released in October 2014, showing footage of the band’s shows at San Siro Stadium in Milan, Italy. In November 2014, One Direction released their fourth album, Four. The last album to include Zayn Malik, singles “Steal My Girl” and “Night Changes” both received platinum status. The album debuted number one in 18 countries, and One Direction became the only group in the 58-year history of the Billboard 200 albums chart to have their first four albums debut at number one. In February 2015, the band embarked on the On The Road Again Tour, playing shows in Australia, Asia, Africa, Europe, and North America. Over 2.3 million tickets were sold with a gross of $208 million. In November 2015, Made in the A.M., their fifth album, was released. Led by singles “Drag Me Down” and “Perfect”, the album reached number one in multiple countries, including the UK, while it reached number two on the US Billboard 200. Following the release of the album the group went on an indefinite hiatus.

Horan enjoyed playing a number of sports while growing up, including golf, soccer, and Gaelic football. In the summer of 2010, while playing football with friends, he injured his knee and was diagnosed with a floating kneecap. The problem recurred several times over the next couple of years, including a 2013 incident where he dislocated his knee onstage during a concert in Antwerp, Belgium. Horan went to the United States for major reconstructive surgery in January 2014, after the tour ended. After the surgery, he was invited to do physical therapy with Chelsea by their manager, José Mourinho. Horan went through more than seven weeks of physical therapy with the members of the team and their physical therapist at their training ground in Surrey.

In May 2014, Horan hosted the Charity Football Challenge at Leicester City’s King Power Stadium to raise money for Irish Autism Action. The celebrity football match had 10,000 spectators and raised about £300,000 for the charity. In 2016, Horan continued to support Irish Autism Action by creating limited edition T-shirts.

In February 2016, Modest Golf, a golf management company that Horan founded together with Mark McDonnell and Ian Watts, was released. Modest Golf has since signed several golf players. In March 2019, Modest Golf earned its first European tour win when Italian golfer Guido Migliozzi, the first golfer that the company signed back in August 2016, won the Kenyan Open. In September 2016, it was announced that Horan had signed a solo deal with Capitol Records. On 29 September 2016, Horan released his debut solo single “This Town”. Since its release, it has peaked at number 9 on the UK Singles Chart and number 20 on the US Billboard Hot 100. On 4 May 2017, Horan released his second solo single “Slow Hands”. It also entered the top 10 in the UK and the top 20 in the US.

In 2016, Horan was actively involved with the Drive, Chip, and Putt initiative that encourages and supports children golfers. Horan also helped promote the Northern Ireland Open.

In an interview with Entertainment Weekly, Horan stated that his upcoming album, Flicker, was inspired by classic rock acts, including Fleetwood Mac and The Eagles, “Whenever I would pick up a guitar, I would always naturally play chords like that, and finger pick a lot and play that folky kind of style.” He also described the collection as having a “folk-with-pop feel to it.” Horan embarked on a worldwide tour, Flicker Sessions 2017, which started in August to promote the album. Horan announced that he had contacted American singer Maren Morris to contribute to his song “Seeing Blind”. In August, he debuted a song titled “On My Own” at Dublin’s Olympia Theatre. On 15 September 2017, Horan released his third single from the album, “Too Much to Ask”.

Flicker was released on 20 October 2017, and debuted atop the Billboard 200. It also reached number one in Ireland and the Netherlands. On 8 November 2017, he performed alongside Maren Morris at the 51st Country Music Association Awards. In 2018, he embarked on the Flicker World Tour to promote the album.

Horan was announced to be joining the Soccer Aid 2016 star lineup fundraiser for UNICEF as an assistant manager and player for the Rest of the World team. In 2017, Horan received an Arnie Award for his work with charities. In 2019, Horan joins UNICEF’s Soccer Aid World XI team, formerly called Rest of the World, alongside retired sprinter Usain Bolt and former Chelsea FC player Didier Drogba. UNICEF’s soccer aid tournament aims to raise funds to benefit children around the world.

In April 2018, Horan opened up on his diagnosis of mild OCD and his anxiety.

In September 2019, Horan stated that he had been working on his upcoming second studio album with Greg Kurstin, who helped him with a ballad entitled “Put a Little Love on Me”. The album’s lead single, “Nice to Meet Ya”, was released on 4 October 2019. On 30 October, Horan announced that he would be embarking on the Nice to Meet Ya Tour in 2020. “Put a Little Love on Me” was released as the album’s second single on 6 December 2019. On 7 February 2020, Horan released the album’s third single, “No Judgement” alongside revealing the album’s title as Heartbreak Weather and announcing 13 March 2020 as the release date.

In June 2020, Horan expressed his support for the Black Lives Matter movement and attended multiple London marches. Horan has also been vocal about the 2020 United States election year and has expressed his distaste for United States President, Donald Trump, on multiple occasions.