The 5-3 Packers, who are second in the National Football Conference (NFC) North, revealed the news on Monday, although the exact length of 50-year-old's improved deal were not disclosed.
McCarthy has been in charge since 2006 and memorably guided the Packers to Super Bowl success with a 31-25 victory over the Pittsburgh Steelers in February 2011.
"We are very happy to extend our relationship with Mike," said Packers general manager Ted Thompson.
"Over the past nine years, he's provided great stability and consistency to the Packers organization and our community as an excellent coach and leader.
"He's a good man and we look forward to the future with Mike as our head coach."
As well as masterminding the Packers' second Super Bowl, McCarthy has reached the play-offs six times and won four divisional titles.