The former The Only Way Is Essex star – who has previously opened up about battling a cocaine addiction that led to two overdoses – posted a message on Instagram saying he had reached the milestone.
“1 year clean and sober,” he wrote alongside a picture of his sobriety medallions.
Adding a heart emoji, Argent said it was “a huge milestone I’m extremely proud of”.
The star revealed last year that he had suffered two near-fatal overdoses.
Argent told The Sun that he was at “rock bottom” and that he had locked himself into his house when the first overdose occurred. His on-off girlfriend Gemma Collins was the one to call the ambulance.
That time Argent said he was told: “You’ve done so much and your heart is so f***** you could die. You have to come to hospital.”
The 33-year-old sought help and weeks before Christmas 2020 he told his followers on Instagram that he was nearing the milestone of a year of sobriety.
“A year ago today on my birthday I was rushed into hospital after a near fatal drug overdose,” he said.
“Today I’m over 11 months clean & sober, If I can achieve this in 2020 with everything against me then I believe I can achieve anything.
“Thank you for your love & best wishes. I will continue to make my family, friends & supporters proud of me.”
He added: “Whenever I feel down or depressed I listen to @thebeatles & it makes me feel better!”