KSI thinks his chart success is "mad".

The 28-year-old star first rose to prominence as a YouTuber, and after achieving his first-ever UK number one album with 'All Over the Place', he's confessed to being staggered by his own success in the music industry.

The rapper - who has worked with the likes of Anne-Marie and Craig David - told OfficialCharts.com: "Your boy did it! Finally got it, a number one album - mad!

"Thank you to everyone who has supported, I wouldn’t have this without you. I’ve been doing music for so long and to finally get this is crazy. Official Charts Company. Number one. I never thought I’d ever get one of these. I have no right – I’m a YouTuber!"

KSI confessed to being shocked by his own success last year.

The YouTuber-turned-rapper - whose real name is Olajide 'JJ' Olatunji - admitted that even he's been surprised by what he's managed to achieve in recent years.

Speaking about collaborating with the likes of Craig David, he said: "Twenty years ago when I was in the car with my parents, we'd listen to 'Seven Days' and 'Fill Me In' ... So I'm like, 'How have I ended up here?'"

KSI has a huge online following, with more than 13 million subscribers to his YouTube channel.

But he's insisted that in spite of his fame and popularity, he won't allow the success to go to his head.

He said: "It's crazy, like, I don't even go into studios. A lot of times, I just play the beat over and over and actually just write in my bedroom."