The news of his death was confirmed by a representative of Carter's team on Saturday (5 November) after Los Angeles police officers found his body at his home in Lancaster, California.
Carter's family are now investigating the cause of death of the singer and TV personality, who was the younger brother of Backstreet Boys member Nick Carter.
Alongside his solo music career, he appeared in an episode of the teen sitcom Lizzie McGuire alongside Duff.
Taking to Instagram, the 35-year-old actor and singer shared a touching tribute to the late star, saying that her 'teenage self' loved him.
She wrote: "For Aaron - I'm deeply sorry that life was so hard for you and that you had to struggle in front of the whole world.
"You had a charm that was absolutely effervescent… boy did my teenage self love you deeply.
"Sending love to your family at this time. Rest easy."
Carter rose to fame when he was just nine years old, releasing his self-titled debut album in 1997.
In 2000, he dropped a second album which went on to earn triple platinum by the Recording Industry Association of America.
The 'struggle' in McGuire's post may refer to the fact that he filed a bankruptcy petition in 2013 following the news that he was more than $2 million in debt.
Carter was open about the fact that he had battled drug addiction in the past, having spoken with the Daily Mail earlier this year to express his frustration over being painted as a 'train wreck' despite being five years sober.
"I realised that I was killing myself and everything was being destroyed around me from it," he told the outlet.
"I was lying to the world and myself. Everybody deserves a second chance. I have not committed any crazy crimes.
"I am not how some people try to paint me. If somebody wants to call me a train wreck, well I've been a train that's been wrecked multiple times and derailed by many different things.
"But I rebuild, get on the tracks and keep going."
Upon the news of his death, Carter's family said they were 'extremely saddened and shocked to confirm' the loss of their loved one.
In a statement to The Independent, they explained: "At the moment his cause of death is being investigated."
The tributes for Carter continue to pour in, with comedian Loni Love sharing a picture of herself and the pop star from when they met on a chat show in 2018.
Describing him as 'funny, talented and cool', she wrote: "I felt that he was trying... he really was just trying to be happy.
"I'm sorry to hear of his passing... Condolences to his family and fans."
If you have experienced a bereavement and would like to speak with someone in confidence, contact Cruse Bereavement Care via their national helpline on 0808 808 1677
Topics: Music, News, Celebrity, TV And Film
