The JIT has been directed to submit a report withing 60 days.
In particular, documents appeared to show that three of Sharif's children - Maryam, Hassan and Hussain - owned offshore holdings in three British Virgin Islands-registered companies.
Interestingly, Pakistan's military intelligence and ISI will be part of the joint interrogation team.
Pakistan, which marks its 70th anniversary of independence later this year, has seen a surge in optimism in recent months.
The sharply worded, 540-page ruling fell short of the bombshell Sharif's opponents had hoped for, allowing him to remain in office while his party, the Pakistan Muslim League-Nawaz, competes in general elections next year.
About 500 security personnel were deployed in advance of Thursday's decision, with access to the Pakistan Supreme Court sealed except for those with special passes.
Khan threatened past year to "lock down" Islamabad, before the supreme court agreed to his petition to investigate the financial allegations.
Rings of security surrounded the supreme country building in anticipation of the verdict.
Opposition leader and lawyers termed the court's verdict as an indictment of Sharif and demanded his resignation.
Fawad Chaudhry of Pakistan Tehreek-e-Insaaf (PTI) said that Sharif should resign as all judges have accepted that money was illegally sent out of the country. Khan asked the media after the verdict.
United Airlines to testify at hearing over dragging incident
Those on the House of Representatives committee were already pressing federal regulators for a thorough investigation last week. No witnesses or precise date was announced, but the hearing comes after a drumbeat of concern from members of Congress.
Zardari told the media, "On what grounds is PML-N celebrating and distributing candies?"
Cyril Almeida, a columnist for the Dawn newspaper, was not surprised by the ruling.
Saadia Toor, associate professor at City University New York, said the scourge of corruption extended far beyond Sharif and offshore wealth.
For some voters, though, the verdict fell short of an acquittal.
"The two judges have declared the PM is disqualified".
They have dismissed the claims as politically motivated.
The detailed judgment of the Supreme Court of Pakistan regarding the Panama Leaks case contained a chart which highlighted the Prime Minister and other respondents' contradictions with regard to the ownership of the London flats.
Maryam Nawaz, the Prime Minister's daughter, immediately tweeted photographs of Sharif in a celebratory mood with his family, embracing his brother Punjab Chief Minister Shahbaz Sharif.
The so-called Panama Papers - 11 million secret documents leaked from Panama-based law firm Mossack Fonseca - set out the offshore financial activities of political and business leaders and the wealthy elite around the world.
Sharif had argued that the London property was bought from the money earned after selling share Gulf steel mill in Qatar and produced a letter by a Qatari prince in his support.