The 26-year-old platinum-selling rapper was found unresponsive at his home in Los Angeles on Friday morning, after reportedly overdosing.

Charlie says the pair had become "really good friends" in recent months.

"I always thought I'd be the one to help him get clean and to lead him on to the path of a good, clean, sober life," he said.

 Puth previously topped the singles chart with his Wiz Khalifa collaboration See You Again

"We talked almost every day and I don't get a lot of friends who come into my life who I hit it off with so quickly," Charlie told E! News.

The Attention singer also tweeted about Mac Miller's death, saying "this really, really sucks".

Charlie says he texted Mac's phone after his death - something he says he has done before when his friends have died.

"Every time someone close to me passes away I always text their phone and I don't know why I do this often."

"I just wrote 'I love you man' and I knew he wasn't going to write back but I just felt like I had to do it anyway."

It was only last month when Mac released his fifth studio album, Swimming.

"He was one-of-a-kind, there was no-one like Mac," Charlie says.

A post-mortem examination is due to be carried out to determine what caused Mac Miller's death.

In a statement, Mac's family said he was a "bright light in this world for his family, friends and fans".

Many artists have paid tribute to him, including his ex-girlfriend Ariana Grande - as well as Ed Sheeran, Drake and Post Malone.

Follow Newsbeat on Instagram, Facebook and Twitter.