A Swiss court on Tuesday found the pair, as well as lawyer Jens Schlegelmilch, guilty of arranging an illegal commission worth $12 million from two Swiss firms nine years ago.
The trio were condemned for awarding a pre-shipment customs inspection contract to Societe Generale de Surveillance (SGS) and Cotecna.
Swiss investigating magistrate Daniel Devaud said his inquiry established that Bhutto and Zardari were paid by SGS and Cotecna "as a result of their unfair management of the public interests of the Islamic Republic of Pakistan."
Six month sentence
With Schlegelmilch, they laundered $11,997,423 in two Swiss bank accounts.
Devaud awarded Bhutto and Zardari a suspended six months prison sentence and fined them $50,000 dollars.
Zardari: Known in Pakistan as
Mr 10 per cent
The former first couple were also ordered to repay the Pakistani government $11,997,423, and to forfeit a diamond necklace worth $180,000 which Bhutto purchased with the ill-gotten gains.
Immediately after the verdict, the ex-premier dismissed the Swiss finding as politically motivated, according to her Pakistani lawyer Farooq Naek.
Host of accusations
A Pakistani court convicted Bhutto and Zardari in the same case in 1999, but the Supreme Court overturned the finding two years later, alleging political bias.
It then ordered a re-trial by a state accountability court.
The couple have been fighting a host of corruption charges since Bhutto was dismissed a second time from power in 1996 on accusations of graft.
Apart from the overturned 1999 conviction, the only other conviction was against Zardari last September.
The couple have long insisted all the charges were politically motivated by their rivals.