Ennis recorded four of his points in the last 2 minutes to help the Orange (18-0, 5-0 ACC) get past their longtime former Big East rivals in their first meeting as members of the Atlantic Coast Conference.
Ennis gave Syracuse a 53-52 lead on a layup with 1:50 remaining, then added another key basket with 32 seconds to go.
C.J. Fair helped out with 13 points and Jerami Grant added 12.
The Panthers (16-2, 4-1) fell for the first time in seven games despite 18 points from Lamar Patterson.
Talib Zanna contributed 12 and 11 rebounds for Pitt.