Rob Lowe is celebrating a major milestone.

On Monday, the 57-year-old actor took to Instagram to announce his 31st year of sobriety from drugs and alcohol.

The "Literally!" podcast host shared an image of himself biking on a beach, wearing a plain grey t-shirt and green pants, but no shoes.

He offered up his signature steely look for the camera.

ROB LOWE SHARES THROWBACK PHOTO IN HONOR OF 57TH BIRTHDAY: 'I AM A GRATEFUL MAN'

"Today I have 31 years drug and alcohol free," said Lowe in the caption. "I want to give thanks to everyone walking this path with me, and welcome anyone thinking about joining us; the free and the happy."

Rob Lowe is celebrating 31 years of sobriety. (Photo by Paul Archuleta/Getty Images)

Rob Lowe is celebrating 31 years of sobriety. (Photo by Paul Archuleta/Getty Images)

He concluded: "And a big hug to my family for putting up with me!!"

His family seemed to have taken notice of the sweet post, as Lowe's son, John Owen Lowe, left a sweet comment.

"So proud of you, dad," he wrote. "Love you."

John himself recently hit three years of sobriety himself, sharing the news of the milestone on Instagram on April 1 alongside a photo of himself posing happily at a restaurant.

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"Three years sober today. Feeling a wave of gratitude that is hard to describe," he wrote at the time. "Life is beautiful and worth living, but man it feels extra good living it the right way (for me)."

The budding actor concluded: "To anybody out there that needs to hear this: it gets SO much better."

Last year, Rob revealed the surprising celebrity that helped encourage him to stay sober.

Rob Lowe's son, John Owen Lowe, recently celebrated three years of sobriety. (Photo by Stefanie Keenan/Getty Images for TOM FORD: AUTUMN/WINTER 2020 RUNWAY SHOW )

Rob Lowe's son, John Owen Lowe, recently celebrated three years of sobriety. (Photo by Stefanie Keenan/Getty Images for TOM FORD: AUTUMN/WINTER 2020 RUNWAY SHOW )

"I’ve been sober for 30 years. When I first got sober, I thought, my life is sober. My fun is done, and I’m not going to be cool anymore," he said at the time, per Entertainment Weekly.

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He continued: "I came home when I was probably sober two or three weeks and I got a call from Steven Tyler, who I did not know. He called to say ‘I heard you are in recovery and I just wanted to say hey, I’m thinking of you dude.’ If it’s good enough for f---ing Steven Tyler, it’s good enough for me."

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He's also gushed over his "St. Elmo's Fire" co-star, Demi Moore, and said that she was "very helpful" to him staying sober as well.