"The kind of allegations that have been made against Kejriwal are unsubstantiated. No one will believe them," Sisodia told the media. "There is no substance in this allegation."
Sisodia said the allegations came just after Mishra was told he was being removed as minister.
"I have been sacked after I spoke out. I have told #LG about all #corruption cases," Mishra said.
Kapil Mishra on Sunday alleged Delhi minister Satyendar Jain gave Rs 2 crore to chief minister Arvind Kejriwal to settle a land deal.
"I kept quiet all this while due to complete faith on Arvind Kejriwal. Day before yesterday, I saw Jain giving Rs 2 crore in cash to Kejriwal. Kejriwal said few things happen in politics. After having seen Jain hand over such a big amount to him, I had to come out. I have handed over the details to Lt Governor Anil Baijal," Mishra said.
"I am also ready to make a statement before the CBI or Anti Corruption Bureau if required," he added.
Mishra had claimed he would "expose" the involvement of certain AAP leaders in an alleged scam in the supply of water.
He was on Friday sacked as Delhi's Water Minister by party convener Arvind Kejriwal after he sided with Kumar Vishwas who has been at loggerheads with the party leadership.
Deputy Chief Minister Manish Sisodia said Mishra was replaced because there were complaints about inflated water bills of consumers and water was not reaching colonies where new lines had been laid.
The party also inducted two new faces -- Seemapuri MLA Rajendra Pal Gautam and Najafgarh legislator Kailash Gahlot -- in the cabinet.
On Sunday, AAP's Okhla MLA Amanatullah Khan had accused Vishwas of being a "BJP-RSS agent" and planning a coup in the party.
Khan resigned from the party's PAC after Kejriwal expressed his displeasure over the matter.
(With inputs from agencies)