Julio Cesar Chavez Jr. -- Socked with DUI Charges

Boxing champ Julio Cesar Chavez Jr. -- son of the legendary Julio Cesar Chavez -- will have to fight to stay out of jail ... 'cause he was just charged with DUI stemming from an arrest earlier this year.

TMZ has learned ... the L.A. City Attorney has decided to hit Chavez with 3 misdemeanor charges ... 2 for drunk driving and 1 for driving without a valid license.

If convicted on all counts, JCC could face up to a year in county jail and a $1,000 fine.

He's due back in court to face the judge later this month.