Stanford commit Maya Doms had room and Natalie Staude put the ball in the right place after tracking it down following Kate Weisner's corner kick in the 76th minute.
Doms one-timed it with her left foot and the ball arched out of reach of the Mexico goalkeeper and into the net, giving Team USA a 3-2 lead.
The score stood, giving The United States U-17 women's national soccer team the title of the CONCACAF Women's U-17 Championships at IMG Academy in Bradenton, Fla. on Tuesday.
The Americans fell behind 1-0 and 2-1 in the first half, rallying each time. Doms put the finishing touch on the victory, racing to the team bench and igniting a celebration.
"It was competitive, physical, tiring mentally and physically," said USA's Kennedy Wesley, also a Stanford commit and who served as team captain for the game. "But both teams got after it and we were able to come out on top this time."
Hannah Bebar and Sunshine Fontes also scored for the U.S., which had clinched a spot in the FIFA Women's World Cup in Uruguay just by reaching the final.
The U.S. opens the U-17 Women's World Cup on Nov. 14 against Cameroon and then meets 2016 World Cup champion Korea DPR three days later. The U.S. will play Germany on Nov. 21.
U.S. goalkeeper Angelina Anderson, who earned two shutouts over the course of the competition, made three saves on the night. She was named the Golden Glove winner as the tournamentâ€™s best goalkeeper.
The USA was also recognized with the tournament's Fair Play award, while Fontes, with five goals, tied for the tournamentâ€™s top scorer with Golden Boot and Golden Ball winner Melchie Dumonay of Haiti.
The Americans claimed their fourth regional title, also winning in 2008, 2012 and 2016.
Menlo School junior Sophia Jones player in her third consecutive contest while Stanford commit Astrid Wheeler did not play.