Harris had 16 assists, 14 points and 12 rebounds in the regular-season finale - the first triple-double in the conference since 2010. Jace Hogan scored 26 points to lead Jacksonville (14-17, 8-6), which shot 57 percent.
Garrett Sams scored 19 points to lead the Ospreys (13-18, 7-7).
J.T. Escobar hit a 3-pointer to get North Florida within three with 17 seconds left but Hogan sank two free throws with 13 seconds remaining for Jacksonville and the Ospreys missed a 3-pointer with nine seconds left.
Jacksonville swept North Florida for the first time since the 2012-13.
The Ospreys will be on the road for their first-round tournament game.
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