Sharif and his daughter were sentenced in absentia to 10 years and seven years in prison, respectively, for failing to explain how they acquired expensive properties in London.
Separately, Maryam was sentenced to one-year imprisonment for submitting false documents.
Imran Khan, chairman of the Pakistan Tehreek-e-Insaf (PTI), political party, holds his tasbih, while having tea on a plane on his way to a campaign rally ahead of general elections in Sialkot, Pakistan July 12, 2018.
A team of doctors, in the presence of Islamabad magistrate and senior police officials at Adiala jail, also conducted the medical examination of Sharif and his daughter Maryam and declared them fit.
No one claimed responsibility for the bombings, but they came days after a suicide bomber dispatched by the Pakistani Taliban killed secular politician Haroon Ahmed Bilour and 20 others at his rally in the north-western city of Peshawar.
The Sharifs' return could shake up an election riven by accusations the military is working behind the scenes to skew the contest in favour of Khan, who describes Sharif as a "criminal" deserving no support. "We don't have a loyalty", the army spokesman said earlier this week. The country has, over the years, seen power see-sawing between the military and civilian leadership.
Local police official Naveed Shah told Reuters his current orders did not include restricting people's movements, but that could change when supporters of Sharif's Pakistan Muslim League-Nawaz (PML-N) party take to the streets.
The Congress Saturday tweeted an old photograph of Prime Minister Narendra Modi and Sharif holding hands and asked: "Nawaz Sharif has been arrested on corruption charges".
He has accused a covert military-judiciary alliance of trying to keep him out of politics and of undermining the integrity of his PML-N party.
Sharif was later allowed by the military regime to go into exile in Saudi Arabia, returning in 2007 before becoming prime minister for a third time in 2013.
As campaigning intensifies, attacks in different areas of the country have stoked fear of more violence in the Muslim country of 208 million where political rallies can draw tens of thousands of people.
In a landmark verdict, the Sharifs were convicted by an anti-corruption court for not being able to prove a legitimate source for funds used to buy a set of upscale London apartments.
Khan's political fortunes were transformed last July when the Supreme Court disqualified three-time premier Sharif in a case that judges only took up when Khan threatened to paralyse the capital Islamabad with his supporters.
In the midst of this, clashes and reports of stone pelting erupted between security forces and the PML-N workers, prior to Nawaz's landing in Lahore.
When the name Imran Khan comes to the fore, the first and foremost memory of Pakistan's 1992 Cricket World Cup victory sparks.