Jones, coming off consecutive player of the week honors, made nine of 11 shots, and scored nine straight Connecticut points in the third quarter after the Mystics had opened a 10-point lead.
Shekinna Stricklen added 12 points, hitting four 3-pointers, for the Sun, who have won 11 straight home games. They went 10 of 21 from distance and made 11 of 12 free throws, including six in the final 35 seconds to end the last threat for Washington.
Connecticut (6-1) has won four straight while Washington (4-2) had its four-game winning streak snapped. Since a season-opening 84-69 loss to Connecticut, the Mystics had not been challenged and were averaging just less than 90 points a game.
Ariel Atkins led Washington with 18 points. Aerial Powers added 14, Elena Delle Donne 13 and Natasha Cloud 12. The Mystics were just 6 of 28 behind the line.
Washington led 37-33 at the half and a 3-point play by Atkins pushed it to 46-36. Alyssa Thomas made a 3-point play and Jones had back-to-back 3-pointers.
Jones made a free throw after Washington coach Mike Thibault was called for a technical and then scored on the ensuing possession to cap a 12-2 run that put the Sun up 48-47.
Stricklen, Jones and Williams made sure Connecticut answered every Washington threat after that.