The top-ranked Serb avoided the post-season exhibitions last month after an exhausting 2015 season in which he won three major titles and reached the final in the other.
The Qatar Open was the only tournament in 16 played in 2015 in which Djokovic failed to reach the final, instead losing in the quarterfinals.
Last year, Djokovic won a career-best 11 titles and finished with an 82-6 record.
"Obviously you never know how you're going to start from the blocks," Djokovic said. "I think I used the offseason very well to train to get my body in the right shape, and I think it was a very good start."
Spaniard Daniel Munoz De La Nava posted the first upset of the tournament, defeating fifth-seeded countryman Feliciano Lopez 3-6, 7-6 (4), 7-5.
Seventh-seeded Jeremy Chardy of France beat Qatari wildcard Mubarak Shannan Zayid 6-1, 6-1.