Smith scored six of her 14 points in the final two-plus minutes and finished with 12 rebounds and six assists - both career highs.
Kahleah Copper scored 16 points, Dana Evans 14 and Courtney Williams had 12 with 11 rebounds and five assists for Chicago. Sika Kone, a 20-year-old rookie, had 10 points and six rebounds. The 6-foot-3 forward was a third-round pick by the New York but was waived by Liberty on May 16.
Crystal Dangerfield hit a 3-pointer to give Dallas (2-1) a 71-70 lead early in the fourth quarter but Evans answered with a pull-up jumper and then a fadeaway, Copper put back her own miss before Smith made a jumper to cap a 9-0 spurt with 6:46 to play and the Sky led the rest of the way.
Mabrey had 15 first-half points and the Sky had 13 assists on 17 made field goals before the break.
Arike Ogunbowale scored 27 points and Satou Sabally had 24 points and eights rebounds for Dallas. Natasha Howard added 14 points, seven rebounds and two blocks and Dangerfield finished with 11 points and five assists.
Mabrey, in her fifth-year season out of Notre Dame, spent the past three seasons with the Wings before being sent to Chicago (3-1) in a four-team trade in February to provide scoring punch to the new-look Sky. A second-round pick by the Los Angeles Sparks in 2019, the guard averaged double figures each season in Dallas, including a career-high 13.6 in 2022.