Kelly was previously under contract through 2017. The new renegotiated pact basically replaces that agreement.
Kelly, 54, has compiled a 55-23 record in six seasons with the Fighting Irish. Notre Dame went 10-3 in 2015 and lost to Ohio State in the Fiesta Bowl.
"I coach football because I believe there are few better avenues for impacting the lives of young men, and I am certain that there is no better place to do that than the University of Notre Dame," Kelly said in a statement.
Kelly is the first Notre Dame coach to take the school to at least six straight bowl games since Lou Holtz (1987-95). His 2012 squad went 12-1, reaching the BCS national title game before losing to Alabama.
Kelly's career record is 226-80-2 over 25 seasons. He coached at Central Michigan and Cincinnati before being hired by Notre Dame after the 2009 season. He went 34-6 in three seasons at Cincinnati from 2007-09.
"In the classroom, in the community and on the playing field, Brian has built the foundation of a great Notre Dame football program -- one that reflects this University's values and its unique relationship to the game of football," athletic director Jack Swarbrick said in a statement. "I could not be more excited about the future of our football program under Brian's leadership, and I am especially thankful that our student-athletes will continue to have the benefit of that leadership in the years to come."