The second-seeded Radwanska broke Kovinic five times and saved all five break points she faced.
The Polish player didn't lose a set in five matches this week to win her 16th career WTA Tour title.
Radwanska became the fifth player to qualify for the year-end championships, joining Maria Sharapova, Simona Halep, Petra Kvitova and Garbine Muguruza in the field. Top-ranked Serena Williams is skipping the tournament to rest and recover from injuries.
Radwanska has qualified for the WTA Finals for the fifth consecutive year.