Anthony Parker added 18 for the Raptors, winners of two in a row and five out of six. Atlanta lost its second straight.
Atlanta trailed by just two after Johnson made a three-pointer with 6:41 remaining in the fourth quarter. Toronto then ran off eight straight points to take an 83-73 lead with 3:30 to go.
The Hawks came no closer than seven the rest of the way.
Toronto has won the last four meetings between the teams.
Notable deaths of 2014 [PHOTOS]
UPI Sports Results for September 19, 2014