The 24-year-old Irish singer thanked fans for their support in a series of posts on Twitter following the album's debut at midnight Eastern time.
"it's time! Flicker is out, finally," Horan wrote to his 35.2 million followers. "I've spent the last year and a half writing and recording this album. It's something that I've worked really hard on and I'm incredibly proud of it."
"This is the first time I've put my thoughts and emotions on paper and then onto record and It feels really good," he added. "I hope you enjoy it. Thank you for everything so far. Lots of love Nialler Xx."
Horan followed up by tweeting, "feeling the love. Thank you all so much. #Flicker is yours now."
He performed Thursday night at a screening of On the Record: Flicker, his short film with Apple Music, in Los Angeles.
"Massive thank you to @AppleMusic for this evening, really appreciate it. Thank you also to the lovely crowd who stood and listened to me," the star wrote.
Flicker includes the singles "This Town," "Slow Hands" and "Too Much to Ask." It also features the title track, "Flicker," which Horan called "the most important track [he] ever wrote" in an interview with Teen Vogue.
"The great thing about songs is that they mean different things to different people," he told the magazine.
"I'm just excited for the fans to listen to the album as a whole and then they can decide what track means the most to them."
Horan came to fame with the boy band One Direction, which started an indefinite hiatus in December 2015.
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