On Wednesday, the singer took to Instagram to commemorate the milestone, saying getting sober was the "BEST thing" she ever did. In her post, Allen, 36, shared three photos of herself posing in a black dress, as well as a screenshot from the Pink Cloud app, which showed the amount of time she's been sober.
"2 years Drug and Alcohol free," she captioned the post. "Getting clean is the BEST thing i ever did, and i've done a lot of cool s---."
Stars and fans alike took to the comments section to congratulate Allen on the incredible milestone.
"Incredible Lils congratulations ❤️❤️❤️ ," model Daisy Lowe wrote, while model Poppy Delevingne commented, "YES BEBE. 🔥"
"13 Reasons Why" star Tommy Dorfman also chimed in, writing, "yessssssssssss"
While appearing on an episode of "The Recovery" podcast back in January, Allen -- who married actor David Harbour last September -- discussed her past struggles with addiction. At the time, the "Smile" singer shared that she began recovery "about five years" prior.
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"I remember being in L.A. and thinking like, 'None of this acting out is working anymore. Maybe I should try heroin,'" Allen recalled. "I'd been in a scene ... and knew that when that thought popped into my head it was time to confront my demons."'
The Grammy nominee went on to reveal that Harbour is also sober.
"I'm in a really happy and healthy relationship," Allen said. "He's sober, has been sober for 20 years now. We're thinking about what we're going to do with the rest of our lives ... I don't have as much as I had then in terms of success and wealth, but I have success and health in my mind, which is more valuable I think."
Later that month, the "Hard Out Here" singer took to Instagram to celebrate 18 months of sobriety.
"18 months clean and sober today. Would recommend!" she captioned a series of photos of herself, including a shot of her holding up a keychain that read, "Clean & Serene For Eighteen Months."