Tayler Hill netted 16 points in the Washington Mystics' 70-52 win over the New York Liberty.
Kia Vaughn tallied 10 points and 12 rebounds for the Mystics (17-17), who clinched the third seed in the Eastern Conference.
Kelsey Bone poured in 11 points and Toni Young added 10 for New York (11-23), which finished the year with seven straight losses.
Sunday marked the final game for 39-year-old Katie Smith. Smith, who had seven points, finished her career as the WNBA's second all-time leading scorer with 6,446 points and its leading 3-point shooter with and 904 made 3s.
Washington took a 17-15 edge into the second and never trailed beyond the opening frame.
The Mystics, who led 33-27 at the break and 52-44 after three periods, closed the game on a 14-4 run.
Washington will face second-seeded Atlanta in the first round of the playoffs.