Although Kelly initially was interested in playing volleyball and not basketball in Rochester Mayo high school (Minnesota) , soon she joined her sister Coco and they made it to a championship in New York, where they lost in the finals. They also helped their school go 27-0 and win the Minnesota state's class 4A championship. Then, they both went to University of Georgia, where both players won a series of awards, including the James E. Sullivan Memorial Award, given to the best collegiate players of all sports combined. They earned that award in 1999, becoming the first pair of twins to earn the award, and joining such luminaries as Carl Lewis, Greg Louganis, Bill Walton, Bill Bradley, Kurt Thomas, Jackie Joyner-Kersee and Janet Evans as receivers of that award.
Kelly Miller ranked second in points among University of Georgia women players with 2,177; second in assists with 639; fourth in steals with 379 and tenth in rebounds with 711. She is the only player in UoG women's basketball to rank among the top ten in points, assists, steals and rebounds. She became the third player in that university's history to pass over 2,000 points, and the third player in SEC conference's history to garner player of the week awards three years in a row.
Coco Miller, meanwhile, was also among the top ten in that school's list among women basketball players in assists and steals. She participated in the World University Games, helping her team to a silver medal. She finished her college career fifth among SEC women in scoring at 16.6, second in free throw percentage at .743% from the free throw line, and eight in steals with 160. She was a finalist for the Naismith award as the player of the year during her final college season.
Coco Miller went on to be picked by the Washington Mystics of the WNBA, where she averages 6.4 points, 2.4 rebounds and 1.7 assists per game, and Kelly Miller was picked by the Charlotte Sting, where she has averaged 4.6 points, 1.7 rebounds and 1.1 assists per game.
In 2001, the Miller twins were the subject of a biographical television movie produced by the Disney Channel.