The case has shone a spotlight on the chronically underfunded healthcare system in the impoverished nation where many have to rely on self-taught or unlicensed medics to receive treatment.
Yem Chroeum, 55, was facing the prospect of life in prison but his murder charge was reduced by the court to a lesser manslaughter offence, his defence lawyer said.
"My client still insists he is innocent," lawyer Em Sovann told AFP by telephone after the verdict was announced.
The rural doctor was convicted of infecting locals in the remote village of Roka in western Battambang province by reusing dirty needles.
For millions of Cambodians -- especially the poor and those in isolated regions -- unlicensed doctors are the only realistic healthcare option for everyday ailments.
World Bank figures say Cambodia, one of Asia's poorest nations, has just 0.2 doctors for every 100,000 people, on a par with Afghanistan.
Similarly impoverished Myanmar has 0.4 per 100,000, while France boasts 3.2 per 100,000.
Much of Cambodia's shortfall is made up by unlicensed practitioners, many of whom are self taught.
Some of those who were infected testified at the trial.
Loeum Lorn, 52, said he and four of his family members had contracted HIV.
"We are his (the doctor's) victims but it was only late on that we discovered we were infected," he told reporters last month outside the trial.
He added that around 10 villagers who were infected, mostly elderly, had since died.
During the trial, prosecutors accused the doctor of hiding the facts and changing his story.
