The bail will remain in force until October 21.
Justice Tirthankar Ghosh passed the order while hearing Pradhan's plea seeking interim bail to enable him to contest and campaign in the Nandigram bypoll.
Court grants three-week interim bail
The High Court observed that Pradhan had filed his nomination papers before his arrest and that the cases against him date back to 2007.
The court also noted that he was not in custody when he was initially arrested and said the State had failed to place material showing that he was wanted in the cases.
Pradhan was arrested in connection with cases stemming from the 2007 Nandigram agitation, including allegations related to murder and other offences.
Earlier relief in 2007 case
Last week, a separate bench of the High Court had directed that Pradhan not be treated as arrested in another 2007 Khejuri case and ordered that no further steps be taken against him in that matter until October 12.
However, a division bench subsequently set aside that order and directed Pradhan to seek bail through the regular legal process.
Pradhan was arrested soon after former West Bengal Chief Minister Mamata Banerjee announced support for the Congress candidate.
Banerjee announced her support for Milan Pradhan after her own party (MAITC) candidate Sanchita Dey Pradhan withdrew her nomination.
Nandigram bypoll on October 6
The Nandigram and Rejinagar Assembly bypolls are scheduled for October 6, while counting of votes will take place on October 9.
Campaigning for the bypolls will end on October 4.