The song has amassed 300 million streams worldwide.
Adetunji, who had no inkling that he'd be nominated, said it's "exciting".
"That's why it was such a surprise, because when it came out I thought it was maybe, you know, those fake prediction lists," he said.
"But then I turned my phone up, because I was in the studio for an hour, and... I was like, why are so many people ringing me and then I realised."
Adetunji was born in Croydon, London, and moved to Belfast when he was 10.
He made his debut back in 2019, posting rap videos to social media while in school.
He managed to gain greater musical recognition posting his music to TikTok resulting in him being snapped up by RCA Records, after being spotted by Bring Me the Horizon’s Oli Sykes due to a song Adetunji made called 'Woke Up.'
His song Kehlani contains elements of R&B melodies and rap..
“It’s taught me a lesson to keep going, no matter what the circumstances are. Your phone is your tool."
"You can do it all. You can do it all from your bedroom,” he said.
America rapper Lil Baby "was one of the first to reach out to" Adetunji after he "first dropped Kehlani".
The rapper asked him to send him some music to listen to.
The American singer-songwriter Kehlani also FaceTimed him asking for an "open verse" when he was out in a club.
"I remember that day like yesterday," he said.
Adetunji has been working on "mixing different drum patterns with R&B-sounding music" for his next project.
He's been working in America, where "the crowds have been taking to my music quite well," he said.
"They loved the unreleased music, which was really reassuring.”
His advice to blooming artists who want to follow in his footsteps is to "always think of new ways of getting your content out there. Always be on the ball".
"If it's not doing, try again tomorrow," he said.
Adetunji said being nominated has taught him that "you can make it happen".
"The world is so big, and there is such a way for people to discover you, so don't give up."
"You only fail when you give up."
Dublin post-punk group Fontaines D.C. have also been nominated for Best Rock Album for their fourth album, Romance, and Best Alternative Music Performance for the single Starbuster.
The 67th Grammy Awards will take place in Los Angeles on 2 February.