Gadkari, who arrived in Mumbai Wednesday morning, was welcomed by hundreds of supporters at the airport.
"There are attempts being made to slander me, to destroy my reputation," he said.
"My assets are worth Rs.12.5 crore and I am ready to face any probe," he told reporters in Hindi.
Gadkari also blamed a section of the media for targeting him and maintained that he had been fighting for the right of farmers and had no association whatsoever with union Agriculture Minister Sharad Pawar and BJP MP Ajay Sancheti - named as involved in an irrigation scam in Maharashtra.
"I have been fighting for the rights of farmers in Maharashtra, especially irrigation in Vidarbha region. Kejriwal says that in my sugar factory, I use 100 percent of the water from the dam - whereas the water used in the factory is less than one percent," Gadkari said.
He also denied his involvement in a 2009 case of a young girl who was found dead in a car parked at his home in Nagpur. Gadkari said he was cleared after a probe in the case, but the media continued to hound him.
He also reiterated that the allegations against his company, Purti Group, were false.
India Against Corruption (IAC) member Arvind Kejriwal had levelled allegations related to land deals in Maharashtra against the BJP chief. The latest allegations against Gadkari are about improper business dealings as chairman of the Purti Group.
The income tax department and the company affairs ministry have begun separate inquiries into Gadkari's firm and its financial dealings with 26 investor companies.
Earlier this month, another IAC member, Anjali Damania, alleged that Gadkari had acquired 100 acres of farmers' land through dubious means for his trust. Gadkari refuted these charges too.