The man had been handed a 150,000 kronor fine ($24,000) in addition to a year in prison. He appealed the ruling as he said he was being treated for the illness and none of the four women he had intercourse with became infected.
According to Swedish law, it is a criminal offence for someone who knowingly carries HIV to have unprotected sex.
The court of appeal in Malmö, southern Sweden, acquitted the man on Tuesday as it said a prerequisite for a conviction was "causing danger for another" and that his actions would have exposed the women to a "real danger" of serious illness.
Experts from the Swedish Institute for Communicable Disease Control (Smittskyddsinstitutet), who recently published a report on HIV, and Professor Jan Albert at the Karolinska University gave testimony and argued that the risk of infection was very small despite the man not using a condom.
The reason for the risk of infection being so small, argued the experts, was that the man was undergoing treatment for the illness and that it was going well.
Last week the Swedish Institute for Communicable Disease Control published a report saying that "Sweden must shed its HIV image".
The report added that HIV was no longer a "death sentence" provided it is caught early and treated, but public suspicion of the illness remains high.
Prior to his acquittal the man had been released from prison ahead of his appeal ruling. One of the reasons why he was released pending his appeal was because the court of appeal had consulted experts at Swedish Institute for Communicable Disease Control about their latest HIV findings.
Earlier this year a Swedish man was ordered to pay more than half a million kronor ($90,000) in damages to a man whom he infected with HIV.
It's estimated that there are 6,500 HIV sufferers in Sweden and that 90 percent of them are being treated for the immuno-deficiency virus.