The Blue Hens (12-7-1) won their first CAA title since 2011 and will visit Providence College in the first round of the NCAA tournament Thursday.
Tabb High graduate Reilly Maw scored his third goal of the tournament 17:13 into the game for William and Mary, heading in a long feed from Remi Frost to put the Tribe (12-7-2) ahead 1-0. But just 2:40 later, a William and Mary mistake led to a tying own-goal.
The Blue Hens took a 2-1 lead in the 28th minute as Jaime Martinez headed a cross from Carlos Perales off the right post and in.
William and Mary qualified for the CAA tourney for the first time in two years and advanced to the final by upsetting top-seeded Hofstra 3-1 on Friday.
"Once again, I'm so proud of this group," William and Mary coach Chris Norris said to Tribe Athletics. "They have been singularly focused on working to be the best they can be. Today, we fought hard and performed pretty well. However, sometimes against good teams, that still doesn't get you the result you desire. Like we've done all year, we will learn from this as we try to get better."
Maw, sophomore Antonio Bustamante and redshirt junior Riley Spain each made the all-tourney team for William and Mary.
The Tribe should return most of its top offensive players for next season including Lafayette High product Reeves Trott, who had an impressive freshman campaign.