Mariah Carey has completed work on her much-anticipated memoirs, insisting it took her 'a lifetime' to summon up the courage and the clarity to write the story.

The Fantasy hitmaker took to social media on Wednesday to let fans know she was done with the tome and it's now in the hands of publishers.

"I want to tell the story of the moments - the ups and downs, the triumphs and traumas, the debacles and the dreams, that contributed to the person I am today," she wrote.

The singer continued: "Though there have been countless stories about me throughout my career and very public personal life, it's been impossible to communicate the complexities and depths of my experience in any single magazine article or a ten-minute television interview."

Bemoaning that "even then, my words were filtered through someone else's lens, largely satisfying someone else's assignment to define me," Mariah said she relished the chance to tell her own story.

The 50-year-old revealed the book is "composed of my memories, my mishaps, my struggles, my survival and my songs."

"I went deep into my childhood and gave the scared little girl inside of me a big voice," she added, "I let the abandoned and ambitious adolescent have her say, and the betrayed and triumphant woman I became tell her side."

Telling fans that writing her memoirs was "incredibly hard, humbling and healing," Mariah concluded that she hoped readers would be "moved to a new understanding, not only about me, but also about the resilience of the human spirit."