The Serb was already assured of topping the rankings again ahead of the season-ender, and confirmed his status by beating number two Roger Federer on Monday night in the London final.
"Before this tournament started, we got the trophy for year-end number one. Then we confirmed it with this World Tour Finals title," Djokovic said.
"This is definitely going to be a strong wind in my back. This season it's going to help me to get better."
Djokovic finished the year with 12,920 points, with the Swiss Federer on 10 265 points after topping the rankings between July and last week. Scotland's Andy Murray came third and injured Spaniard Rafael Nadal is fourth.
ATP Top 10:
1. Novak Djokovic, Serbia, 12 920 points2. Roger Federer, Switzerland, 10 265
3. Andy Murray, Britain, 8 000
4. Rafael Nadal, Spain, 6 795
5. David Ferrer, Spain, 6 430
6. Tomas Berdych, Czech Republic, 4 605
7. uan Martin del Potro, Argentina, 4 480
8. Jo-Wilfried Tsonga, France, 3 490
9. Janko Tipsarevic, Serbia, 2 990
10. Richard Gasquet, France, 2 515