Ex-UFC Star Dustin Poirier Arrested For Allegedly Being Drunk In Public

It wasn't exactly the Father's Day Dustin Poirier had in mind ... the retired UFC legend was arrested early Sunday evening in Georgia, TMZ Sports has learned.

Poirier, 37, was booked for "Public Drunk" -- a misdemeanor -- at 6:38 PM ... before being released several hours later, a quarter after 10 PM.

It's unclear what led up to Dustin's arrest.

On Sunday, Dustin reposted a "Happy Father's Day" post his wife shared with her followers on Instagram ... showing DP with his two children, and everyone is all smiles.

Public drunkenness can carry up to one year in jail and/or a fine, if convicted.

Poirier, the former UFC Interim Lightweight champ, was one of the best 155 lb. fighters of his generation.

Dustin fought Conor McGregor three times, beating him twice. He also beat Michael Chandler, Max Holloway, Eddie Alvarez, and Justin Gaethje, among many others.

Poirier retired a year ago ... after his final fight at UFC 318.

Dustin made his initial court appearance on Monday morning.