Demi Lovato celebrated her five-year sobriety with a post on her Instagram profile, thanking fans for support.
The 24-year-old former child star said her struggle with addiction has been "quite the journey", and said "there were many times I wanted to relapse".
Lovato shared a photo of the 12 steps programme, awarding her sobriety for five years, 60 months, 1,827 days or 43,813 hours.
"So grateful," she wrote.
"It's been quite the journey. So many ups and downs. So many times I wanted to relapse but sat on my hands and begged God to relieve the obsession," she added.
"I'm so proud of myself but I couldn't have done it without my higher power (God), my family, friends, and everyone else who supported me. Feeling humbled and joyful today. Thank you guys for sticking by my side and believing in me."
Lovato, who started her career as a Disney channel star, has been vocal about her struggle with drugs and alcohol, and how it led to an eating disorder and self-mutilation.
In 2010, she left a tour with the Jonas Brothers and entered rehab for three months, after moving to a sober living house for another year.
Diagnosed with bipolar disorder, Lovato has been a vocal advocate for mental health reform.
Inspired by her own struggles, Lovato recently executive-produced a documentary called Beyond Silence, on bipolar disorder, schizophrenia, depression and anxiety.
"You can hear in the documentary how different they are, but also how alike they are," she told Variety magazine.
"It's important that we get that message out there because mental health is so important - it's just important as physical health."
:: Anyone feeling emotionally distressed or suicidal can call Samaritans for help on 116 123 or email firstname.lastname@example.org in the UK. In the US call the Samaritans branch in your area or 1 (800) 273-TALK.