The third-seeded Serb served well throughout, was only taken to deuce in two games and never faced a break point.
He also ran his sixth-ranked Czech opponent around the court at the O2 Arena, using a variety of forehands and backhands to send Berdych sprinting from side to side.
“There is no easy match, easy opponent, whatever,” Djokovic said of the season-ending tournament, which brings together the top eight players in the world.
Djokovic's strong performance aside, Berdych's biggest problem may have been his serve.
The Czech landed only 48 percent of his first serves, and although he only had three double-faults, two of them came in the first game - on the opening point and on break point.
“That is the worst case in every match, if you start pretty bad with a service game and you just give the break up to your opponent,” Berdych said. “And if you play Novak, it's even tougher.” After holding to 2-0, Djokovic then had four break points in the third game, but Berdych was able to hold on and stay in the set. Djokovic, however, broke again in the final game of the first set and then added another in the second game of the second.
“To start off with a break for me was very important,” Djokovic said. “I was trying to focus on my game and do the things that I planned to do tactically with my coach. I think I did well.” Football great Diego Maradona was in the audience for the second day in a row, and Djokovic quipped that the Argentine helped him with his tactics.
“We're working on some specifics, like how to play with hands,” Djokovic said of Maradona, who is famous for his “Hand of God” goal against England at the 1986 World Cup.
Djokovic won the ATP Finals in 2008, but last year failed to advance out of the group stage. Berdych, the only player in the field without an ATP title in 2010, is making his debut.
Berdych has lost four of the five matches he has played against Djokovic, but his one victory came in this year's Wimbledon semifinals.
Later, top-ranked Rafael Nadal was to play Andy Roddick.
On Sunday, Roger Federer and Andy Murray won their opening Group B matches and will face each other on Tuesday. David Ferrer will go up against Robin Soderling in the other match.
In doubles, Mahesh Bhupathi of India and Max Mirnyi of Belarus beat Lukasz Kubot of Poland and Oliver Marach of Austria 7-6 (2), 6-4. In the late match, Daniel Nestor of Canada and Nenad Zimonjic of Serbia were to play Wesley Moodie of South Africa and Dick Norman of Belgium.
