Behanan was shown the door for an unspecified violation of university policy, the coach told reporters, divulging only that the junior's conduct "away from the lines" was unacceptable.
Off the court, the 6-foot-6 Cincinnati native "just did not do the right things, over and over and over," resulting in his dismissal, Pitino said.
Behanan has averaged 7.6 points with 6.3 rebounds this season but was held scoreless with a team-high seven rebounds in Saturday's 73-66 loss to Kentucky.
His dismissal followed a suspension in October and subsequent reinstatement in November.
"The university has gone to the mat for him," the coach added. "We've given him every opportunity to make it here at the university. Unfortunately, it's come to a difficult detour and his road has set our basketball team back immensely, from a basketball technical standpoint."
During the Cardinals' national championship season, Behanan averaged 9.8 points and 6.5 rebounds, including a 15-point, 12-rebound game in Louisville's 82-76 win over Michigan in the title game.