Rodriguez faces up to nine months in prison and $10,000 in fines if convicted of the misdemeanor charge, according to Patch.com, which first reported the filing in Waukesha County Circuit Court.
According to that report, police say that Rodriguez struck his fiancée after she accused him of cheating on her. The alleged incident occurred in the early hours of Sept. 18 at Rodriguez's home in Wales, Wis., a town about 25 miles west of Miller Park.
Rodriguez pitched for the Brewers from July 2011 through the end of this season. He filed for free agency this week.
The Brewers have not commented on the matter since it occurred, other than to say club officials were aware of the ongoing legal issue.
Rodriguez is scheduled to make an initial court appearance on the morning of Nov. 12.
In 2010, Rodriguez was charged with assault and harassment following an altercation involving his father-in-law at Citi Field in New York. He pled guilty to lesser charges and underwent anger management classes.
In a separate news item, USA Today reported that Rodriguez reached an out-of-court settlement Wednesday in a lawsuit against his former agents. He alleged that they lied to him about filing a no-trade clause in his contract with the Mets.
The absence of such a clause allowed New York to trade Rodriguez to Milwaukee in July 2011 for two Minor League players and salary relief.
USA Today, citing an anonymous source, said Rodriguez received more than $2 million in Wednesday's settlement.
The reliever is now represented by agent Scott Boras.