There were 700,000 fewer new infections last year than in 2001, according to a new World AIDS Day report by the Joint United Nations Program on HIV/AIDS (UNAIDS).
More than half of the countries reporting drops are in sub-Saharan Africa, which has some of the highest HIV rates in the world.
"The pace of progress is quickening. What used to take a decade is now being achieved in 24 months,” Michel Sidibé, the executive director of UNAIDS, told the UN News Service. "We are scaling up faster and smarter than ever before.
"It is the proof that with political will and follow-through, we can reach our shared goals by 2015."
AIDS-related deaths fell by more than 25 percent worldwide over the last six years, while the number of people getting treatment is up 63 percent, CNN reported.
Better access to treatment is the primary reason behind the slowed HIV/AIDS progression.
Some 34 million people were living with HIV at the end of 2011, while 2.5 million new infections were reported and 1.7 million people died, according to Reuters.
World AIDS Day is Dec. 1.