Ellington put Cleveland in front by scoring on a dunk with 56.4 seconds remaining, helping boost the Cavaliers to their fifth win in eight games.
Cleveland trailed by eight going into the final period, but produced a 36-point fourth quarter during which Kyrie Irving scored 11 of his 20 points. Irving also had 10 assists and seven rebounds and his steal set up Ellington's go-ahead slam.
Ellington and Tristan Thompson both had 16 points and Thompson added 12 rebounds.
Utah was led by 25 points off the bench from Gordon Hayward.
Celebrity Families of 2014 [PHOTOS]