Los Angeles, California - Miley Cyrus has no regrets about her "messed up" younger years, as made clear by her emotional new single, Used To Be Young.

The 30-year-old unveiled her latest song and accompanying music video on Friday, marking her first follow-up to Endless Summer Vacation.

Used To Be Young sees Miley reflect on her journey into adulthood and the unrelenting criticisms she faced as a young woman in the spotlight.

The music video follows a close-up shot of the Flowers singer in alternating light and shadow, and she tearfully belts out the track.

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"I know I used to be crazy / I know I used to be fun / You say I used to be wild / I say I used to be young," she sings.

Paying a knowing nod to her Disney Channel years, Miley donned a t-shirt featuring Mickey Mouse under a red sequin body suit for the video.

Ahead of the single's release, Miley revealed that Used To Be Young was two years in the making as she set her sights on "painting a sonic picture" of her life so far.

In an Instagram post, Miley revealed that Used To Be Young came out of feeling "misunderstood" and explained that she hoped it portrayed the "unfinished yet complete" journey of her career thus far.

"The time has arrived to release a song that I could perfect forever," she said. "Although my work is done, this song will continue to write itself everyday."

Along with dropping the new single, Miley debuted a new TV special on Thursday called Endless Summer Vacation: Continued (Backyard Sessions).