Jefferson, a leader of the DFW T-Jack Elite team, won it for the squad's former leader.
Backed by a strong defense, DFW, made up mostly of rising seniors, defeated the Fairfax Stars, 58-36, Sunday in the Nike Nationals Gold championship game at the Riverview Park Activities Center.
It was a win in memory of Marques Jackson, who died of a heart attack last year.
"We did it for our coach," Jefferson said. "This is the last time we can do it."
DFW, from Dallas-Fort Worth, Texas, rarely trailed in a game that was secured with a 12-0 run in the second half.
The Fairfax Stars struggled with turnovers, whether it was because of offensive fouls or DFW steals.
Jefferson, who has committed to Connecticut, scored four points during the decisive run, on one play taking advantage of a bad pass to the backcourt by scooping up the ball and going in for an easy layup. She had eight points in the game.
Brianna Turner, a rising sophomore, scored a team-high 12 points for DFW.
The Stars' Courtni Green led all scorers with 13 points and tried to start a comeback when she put up seven quick points early in the second half.
But DFW's Jordan Jones hit back-to-back 3-pointers to halt one small Fairfax Stars rally, and the defense took over from there, helping DFW score 22 of the last 27 points.
The victory was emotional for DFW players.
"I'm just speechless," Turner said. "Words can't describe it."
In Sunday's other championship contests, the Cy-Fair 15U team beat the North Tartan 15U club, 67-64 in overtime to win the Juniors Championship.
In the Nationals Silver championship game, the Georgia Metros controlled the second half in a 58-46 triumph against West Coast Premier.
Washington County's Allisha Gray was the star, scoring 24 points -- 17 in the second half -- and she also dominated defensively for the Metros.
Gray routinely drove to the hoop, earning fouls or getting baskets, as the Metros won both of their Sunday games.
In the morning, Gray scored 20 points as the Metros defeated Boo Williams, 60-42, in a Silver bracket semifinal.
"We started playing team ball," Gray said about the second half. "When we play as a team, all we do is win."