The 13th-ranked Cardinals, who are expected to receive an at-large bid to the NCAA Tournament, forced overtime when Earl Clark scored on a rebound with 30 seconds left in regulation.
Pittsburgh, however, seized control in the extra period and kept alive its hopes of reaching the conference tournament championship game for the seventh time in eight years.
Sam Young scored 21 points for the Panthers, seeded seventh in this tournament and a first-round winner over Cincinnati. Pittsburgh has won five of its last six games.
Pittsburgh (24-9) scored the first four points of overtime and Louisville cut its deficit to two on a basket by David Padgett. Ramon and Fields then hit back-to-back field goals to boost the Panthers in front by six and Louisville could not recover.
Louisville (24-8) also lost its final game of the regular season and has now dropped two in a row for the first time since December. The Cardinals were led by Clark with 19 points.