"I haven't spoken to him in a few months or whatever, and haven't seen him in a while, so I'm looking forward to seeing him," Horan, 23, told ET's Cameron Mathison.
Malik, who left the pop band in March 2015 to pursue a solo career, will of course be in attendance, as his girlfriend, Gigi Hadid, is co-hosting the live show with Jay Pharoah. The "Pillowtalk" singer is also up for the New Artist of the Year award, alongside Alessia Cara, The Chainsmokers, DNCE and Shawn Mendes.
And although Horan is reuniting with Malik at the star-studded show, he admitted it was a bit weird walking the red carpet without the rest of his 1D pals -- Harry Styles, Louis Tomlinson and Liam Payne -- by his side. This marked Horan's first red carpet as a solo artist.
"Yeah that's the thing I been asked a lot today," he dished. "It's obviously different, buts it's different because there's no one else around, but I've been enjoying it so far, the performances that I've done and it’s been fun and yeah I just really enjoyed it."
The Irish heartthrob, who is taking the stage to perform Sunday night, said he's incredibly happy to have the support of his fans.
"I'm looking forward to this," he gushed of his highly-anticipated performance. "This is a show that [One Direction] had success at back in previous years, and had some good performances and had some great nights at, and I'm looking forward to making a few more memories."
"If you didn't have the fans in there, I would be a lost soul," he added. "It's great though. [1D] got to perform in front of such great crowds, and this [solo] one will be no different, I imagine."
As ET previously reported, Horan surprised fans by debuting his solo single, "This Town," via Twitter in September. "Been workin in the studio, wanted to share this song I just wrote with u guys," he tweeted. 'Thank you for always being there."