Jay Cutler Reports To Jail For DUI Sentence

Jay Cutler is back behind bars ... TMZ Sports has learned he reported to a Tennessee jail on Monday to begin serving his DUI sentence.

Records we've obtained show the ex-NFL star was booked into Williamson County Jail at around 8 AM PT ... and the former quarterback is now expected to remain there until Friday.

Cutler, of course, was ordered to spend four days in the slammer last month ... after he pleaded guilty to one count of misdemeanor DUI.

A judge also required Kristin Cavallari's ex-husband to pay a $350 fine, and go on supervised probation for one year. Cutler additionally was ordered to attend a DUI safety class ... and his Tennessee license was revoked for one year.

It all, as you know, stems from Oct. 17, 2024 ... when the 42-year-old was accused of exhibiting signs of being intoxicated following a traffic accident in Franklin.

Authorities alleged Cutler rear-ended a car, and when officers showed up to investigate the scene, he reeked of booze, had bloodshot eyes ... and was slurring his words.

Cutler -- who was arrested over the incident -- was later sued by a man who claimed Cutler was "at fault" for the accident. In the lawsuit, the plaintiff, Perry Lee, stated he sustained injuries in the collision and is in daily pain.