6:36 AM PT -- Lil Baby's attorneys, Drew Findling and David Chesnoff, tell TMZ ... "To be clear, Dominique Jones has a valid Georgia Carrying a Concealed Weapon (CCW) Permit. On his behalf we are actively investigating the facts and circumstances surrounding his arrest in Las Vegas."

Law enforcement sources tell TMZ -- Lil Baby was seen at the Encore in Vegas in the club, and was seen on video being passed a gun. After cops arrived and investigated ... he was arrested for carrying a concealed firearm without a permit.

Nevada does not recognize Carry Concealed Weapon permits issued in Georgia.

Lil Baby landed behind bars Monday in Las Vegas ... 'cause he got busted for possessing an illegal weapon.

The rapper (real name: Dominique Jones) was arrested Monday night for carrying a concealed weapon without a permit – a felony – and hauled off to the Clark County Detention Center, where he was being held on $5,000 bail.

The Las Vegas Metropolitan Police have yet to release details about the alleged crime, but we'll update you once we get more info.

By the way ... Lil Baby has seen the inside of a jail cell before.

In 2019, he was cuffed in Atlanta for failure to signal, eluding police and reckless driving.

Two years later, Baby was arrested in Paris, France, after police caught him with weed inside a car.