The state-run National AIDS Control Council (NACC) said the growing use of life-prolonging therapy averted around 57,000 deaths in 2006.
"The annual death of adult AIDS deaths in Kenya reached a peak of about 120,000 in 2003. It would have stayed at that level for the next three years were it not for the increased number of people on anti-retroviral therapy," NACC said in a statement.
The council also reported a drop in new infections from 60,000 in 2005 to 55,000 last year, but stressed that most new infections were occuring among young people.
At least 1.3 million people are currently living with HIV/AIDS in Kenya, 65 percent of whom are women between the ages of 19 and 45, according to NACC statistics.
Last year, President Mwai Kibaki announced that public hospitals would no longer charge HIV/AIDS patients for anti-retroviral drugs in a new bid to fight the deadly disease.
Since 1984, at least 1.5 million people are said to have died from AIDS in Kenya, according to health ministry estimates.
Sub-Saharan Africa accounts for almost two-thirds of all people infected with HIV and 72 percent of global AIDS deaths, according to UNAIDS.
As of June last year, around one million Africans were receiving antiretroviral drugs. This was still less than a quarter of the estimated 4.6 million people in need of the drugs on the continent.