He was convicted at a retrial in March of accepting illegal payments from an American businessman while he served as mayor of Jerusalem and trade minister.
Last year, he was sentenced to six years in prison for accepting bribes.
Olmert has denied any wrongdoing and will remain free until his appeals against both convictions are heard.
A Supreme Court decision on the first appeal is expected in the next couple of months.
If he is unsuccessful OImert will become the first former head of government in Israel to be jailed.
Olmert served as prime minister from 2006 to 2009.
He was forced to resign amid a flurry corruption allegations, which ended his political career and disrupted the peace process with the Palestinians.
In 2012, Olmert was acquitted of fraud, concealing fraudulent earnings and breach of trust in connection with donations received from a New York-based financier, Morris Talansky between 1997 and 2005.
However, a retrial was ordered after a former aide, Shula Zaken, accepted a plea bargain and testified against Olmert. Ms Zaken gave prosecutors diary entries and tape recordings of conversations in which Olmert referred to receiving the money.
Olmert was found guilty of fraud and breach of trust in March and on Monday was sentenced to eight months in jail. He was also given a suspended sentence of an additional eight months and fined 100,000 shekels ($25,000; Â£16,000).
The Jerusalem District Court said the sentence recognised Olmert's contributions to Israeli society, but noted that "a black flag hovers over his conduct".
Olmert's lawyer Eyal Rozovsky said they were "very disappointed" by the sentence.
The former prime minister has always insisted that he is innocent and has described the allegations against him as "a brutal, ruthless witch-hunt".
The 69-year-old is also appealing against the six-year sentence he was given in May 2014 in connection with a real estate deal at took place when he was mayor of Jerusalem in the 1990s.
He was convicted of accepting bribes in return for speeding up a controversial residential development, known as Holyland, in the heart of the city.

Some German newspapers criticised the cartoon, while the German vice-president of the European Parliament called it "tasteless".
The cartoonist, Edel Rodriguez, said the image represented "the beheading of democracy".
US-German relations have deteriorated under President Trump, who has criticised the policies of German Chancellor Angela Merkel.
He said last month that her policy of welcoming masses of migrants who arrived in Germany had been a "catastrophic mistake". His trade adviser also recently attacked Germany for gaining unfair trade advantages from a "grossly undervalued" euro.
The front cover image is similar to one that appeared on the front page of the New York Daily News in December 2015, also showing Mr Trump beheading the Statue of Liberty but in a less gory fashion.
Mr Rodriguez, who arrived in the US as a political refugee from Cuba in 1980 told the Washington Post that he wanted to make a comparison between the Islamic State and Donald Trump, saying "both sides are extremists".
Der Spiegel editor Klaus Brinkbaumer wrote in an editorial that Mr Trump was "attempting a coup from the top" and wanted to "establish an illiberal democracy".
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The White House has accused liberal media groups of false and irresponsible reporting designed to smear President Trump and the new administration.
Alexander Graf Lambsdorff, a member of the Germany's Free Democrats and vice-president of the European Parliament, said the cover said more about Der Spiegel journalists than Mr Trump.
"The cover plays on the lives of terror victims in a very nasty way," he told Bild.
Several other magazines are using the front covers of their next editions to comment on the US president and his policies.
Bloomberg Businessweek shows Mr Trump holding an executive order, which says: "(Insert hastily drafted, legally dubious, economically destabilizing executive order here)."
British weekly The Economist, which has endorsed both Republican and Democratic presidents, pictures President Trump throwing a molotov cocktail.
The New Yorker, a liberal magazine which endorsed Hillary Clinton, shows the Statue of Liberty's flame extinguished.
The conservative National Review's cover story defends nationalism, which it says critics of Mr Trump's inauguration speech wrongly see as dangerous.
A court in Jerusalem has sentenced the former Israeli Prime Minister, Ehud Olmert, to eight months in prison for fraud and breach of trust.
[NEXT_CONCEPT]
Germany's influential weekly news magazine Der Spiegel has come under fire for a cover image showing US President Donald Trump beheading the Statue of Liberty.