Cappie Pondexter added 16 points for the Sky (4-4).
Chicago went on a 14-3 run in the first quarter for a 22-9 lead and led by double figures the rest of the game. The Sky held a 60-36 lead at halftime behind 10 points apiece from Delle Donne and Jessica Breland. Chicago made 24 of 38 field goals (63 percent) and hit all 10 of its free-throw attempts in the half.
Atlanta cut it to 80-67 with 5:56 left in the fourth quarter. Chicago answered with a 9-0 run, capped by Pondexter's 3-pointer.
Allie Quigley added 16 points in 19 minutes to help Chicago win its third straight game. The Sky, ranked No. 7 in the AP WNBA poll, have won six in a row over the ninth-ranked Mystics.
Emma Meesseman led Washington (2-6) with 13 points.