The Sharif brothers were accused of misusing their authority and accumulating wealth beyond their means.
Former military dictator Pervez Musharaf, who deposed Sharif in 1999, had instituted the cases in 2000, alleging that the brother-duo used a paper mill as a cover for money laundering during the late 1990s.
The National Accountability Bureau court, however, said the Sharif brothers, along with Nawaz's wife Kulsoom Nawaz, daughter Maryam Nawaz and nephew Hamza Shahbaz, were absolved of all corruption charges, including possession of illegal assets.
He said the case was pending for 14 years and not a single witness had appeared in court.
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It is a major victory for the embattled prime minister, facing a barrage of corruption and vote rigging charges by cricketer-turned-politician Imran Khan and a populist cleric named Tahirul Qadri.
Khan wants Sharif's ouster over alleged rigging in last year's poll which his party lost, while Qadri wants to bring a revolution in the country. They are agitating since August 14.
Meanwhile, another case accusing the Sharif family of defaulting over a bank loan in relation to their Ittefaq Foundries was adjourned by the court to October 2.