The 21-year-old German is the youngest player in nine years to reach the final of tennis elite season-ending event, reports Efe news.
With the Sunday victory over Serbia's Djokovic, who has 14 Grand-Slam titles to his credit, Zverev will climb to fourth in the year-end rankings. The rising star got to the final by defeating Swiss great Roger Federer 7-5, 7-6 (7-5) on Saturday, reports Efe news.
"I really cannot describe it. It's the biggest title I have ever won," Sascha, as he is known, said during the trophy presentation at London's O2 Arena.
Turning to Djokovic, he said: "I want to congratulate you for the second half of this year. You barely lost a match all year though you lost to me. I want to mention how good a person you are."
"You deserved to win and well done," Djokovic told Zverev. "You are still quite young and you have had an amazing career."