J.T. Barrett -- Ohio State QB Pleads Guilty ... In Drunk Driving Case (Video)

Ohio State quarterback J.T. Barrett pled guilty to operating a vehicle under the influence -- stemming from a Halloween arrest for driving while intoxicated ... and apologized for his behavior in court.

20-year-old Barrett was arrested on October 31st at a police checkpoint near the OSU campus -- cops say his B.A.C. was .099 ... well above the .02 limit for people under the legal drinking age.

But Barrett struck a plea deal with prosecutors -- in which he pled guilty to the OVI charge, and in exchange a related charge (backing without safety) was dismissed.

As for his punishment, Barrett will NOT spend any time behind bars -- instead, his driver's license was suspended for 180 days and he must pay roughly $500 in fines and court costs.

During today's hearing, Barrett told the judge ... "I just wanted to apologize to my family for this embarrassment and also to the Ohio State football program and also Buckeye Nation."

He added, "I never wanted to hurt Ohio State for what it's done for me as a player and also as a person and I'm truly sorry for that."

Barrett was suspended from last week's game -- but will be back on the field when the Buckeyes take on Illinois on Saturday.