David Irving, who had pleaded guilty and insisted during his one-day trial that he had had a change of heart and now acknowledged the Nazis' World War II slaughter of six million Jews, had faced up to 10 years behind bars.
Before Monday's verdict, Irving conceded he had erred in contending there were no gas chambers at the Auschwitz concentration camp.
Irving said: "I made a mistake when I said there were no gas chambers at Auschwitz."
He also expressed sorrow "for all the innocent people who died during the Second World War".
Irving's lawyer immediately announced he would appeal the sentence.
Elmar Kresbach, the lawyer, said: "I consider the verdict a little too stringent. I would say it's a bit of a message trial."
Irving appeared shocked as the sentence was read out. Moments later, an elderly man who identified himself only as a family friend called out: "Stay strong, David - stay strong," before he was escorted from the courtroom.
Irving, 67, has been in custody since his arrest in November on charges stemming from two speeches he gave in Austria in 1989 in which he was accused of denying the Nazis' extermination of six million Jews.
"I made a mistake when I said there were no gas chambers at Auschwitz"
Earlier on Monday, he told journalists he considered it "ridiculous" that he was standing trial for remarks made 17 years ago.
Handcuffed and wearing a navy blue suit, he arrived at court carrying a copy of one of his most controversial books – "Hitler's War," which challenges the extent of the Holocaust.
Irving's trial was held amidst new - and fierce - debate over freedom of expression in Europe, where the printing and reprinting of unflattering cartoons of the Prophet Muhammad has triggered violent protests worldwide.
Kresbach, Irving's lawyer, said last month the controversial Third Reich historian was getting up to 300 pieces of fan mail a week from supporters around the world, and that while in detention he was writing his memoirs under the working title "Irving's War".
Irving was arrested on 11 November in the southern Austrian province of Styria on a warrant issued in 1989.
He was charged under a federal law that makes it a crime to publicly diminish, deny or justify the Holocaust.
Irving had said there was no
proof Nazis massacred the Jews
Irving had tried to win his provisional release on $24,000 bail, but a Vienna court refused, saying it considered him a flight risk.
Within two weeks of his arrest, he asserted through his lawyer that he had come to acknowledge the existence of Nazi-era gas chambers.
In the past, however, he has claimed that Adolf Hitler knew little if anything about the Holocaust, and has been quoted as saying there was "not one shred of evidence" the Nazis carried out their "Final Solution" to exterminate the Jewish population on such a massive scale.
Irving, the author of nearly 30 books, has contended most of those who died at concentration camps such as Auschwitz succumbed to diseases such as typhus rather than execution.
In 2000, Irving sued Deborah Lipstadt, an American Holocaust scholar, for libel in a British court, but lost. Charles Gray, the presiding judge in that case, wrote that Irving was "an active Holocaust denier ... anti-Semitic and racist".
Irving has had numerous run-ins with the law over the years.
In 1992, a judge in Germany fined him the equivalent of $6000 for publicly insisting the Nazi gas chambers at Auschwitz were a hoax.