The couple have been the focus of multiple graft investigations since Najib's surprise election defeat in 2018, when voters' anger over a separate, multi-billion-dollar corruption scandal ended his nine years in power.
A flamboyant figure by Najib's side, Rosmah was widely scorned in Malaysia for her extravagant lifestyle and penchant for Hermes Birkin bags, and faced repeated questions over her influence in government matters.
Rosmah will also have to pay a fine of 970 million ringgit ($A316 million) - a record amount in Malaysia's history - over three bribery charges, Kuala Lumpur High Court Judge Mohamed Zaini Mazlan said.
She will remain free on bail pending appeals to higher courts.
Rosmah, dressed in a yellow baju kurung - a traditional Malaysian long blouse and skirt - and matching headscarf, addressed the judge tearfully after the verdict.
"I must admit that I'm very sad with what happened today," she said.Â
"Nobody saw me taking the money, nobody saw me counting the money ... but if that's the conclusion, I leave it to God."
Her lawyers asked for a one-day jail sentence, while prosecutors sought "maximum or near maximum".
Rosmah, 70, pleaded not guilty to the three charges of soliciting and receiving bribes between 2016 and 2017 to help a company secure a $US279 million solar power supply project from Najib's government.
Prosecutors say Rosmah sought a bribe of 187.5 million ringgit ($A61 million), and received 6.5 million ringgit from an official of the company that won the project.
Rosmah argued she was framed by her former aide and several government and company officials involved in the project.
She also faces 17 charges of money laundering and tax evasion in a separate case.
Her lawyer, Jagjit Singh, said Rosmah was shocked with the verdict.
"The fine imposed today is unprecedented ...To say she is upset is putting it mildly," he said.
