Hardy, 26, batted .283 with 24 home runs and 74 RBIs in 146 games last season and helped the Brewers win the National League Wild Card.
Hardy, who made $2.65 million last year, is the third player in club history to hit 20 or more home runs in two separate seasons as a shortstop, joining Robin Yount and Jose Hernandez.
The Brewers still have five players who are arbitration eligible: pitchers Dave Bush and Seth McClung, first baseman Prince Fielder, outfielder Corey Hart and second baseman Rickie Weeks.
Fielder and Hart are eligible for the first time.
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.