Hart will be paid $26.5 million through the 2013 season -- $6.5 million in 2011, $9 million in 2012 and $10 million in the last year of the deal - the Brewers' official Web site reported.
The deal includes a $1 million signing bonus and eliminates Hart's final year of arbitration eligibility.
Hart is having his best year as a pro, batting .288 with 23 homers and 72 RBI in 92 games. He was named to the all-star team this summer, his second such selection.
"The Brewers are very excited to have Corey signed for the next three years," Brewers General Manager Doug Melvin said. "He is one of our drafted and developed players and with his two-time all-star performances, Corey deserves this contract that will provide his family security."
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