He's making cases against Jordan Williams, John Stringer and Cameron Slater in the order of $300,000, $600,000 and $650,000 respectively.
He's made the announcement at a press conference in Auckland this afternoon.
He will also be releasing a booklet that outlines the "campaign of defamatory lies" he claims was purposely launched to undermine him.
Slater said he first heard about the defamation claim this afternoon and had not been served court papers.
He had two words for Mr Craig: "Bring it."
The blogger said he had "not one single concern" about the legal action because he was capable of funding his defence and had evidence to back up everything he published about Mr Craig.
"New Zealand can find out once and for all what a ratbag Colin Craig is," he said.
Mr Slater said if someone was going to stand for Parliament, it was important the public knew about their background, especially if it contrasted with their Christian values.
Asked about Mr Craig's allegations of "dirty politics", Mr Slater said: "A: So what? B: Politics is dirty full-stop ..."
Mr Stringer, a former Conservative Party board member and candidate who is based in Christchurch, said this afternoon that he stood by everything he had said about Mr Craig.
He said he had never met Slater or Williams, though he had corresponded with Slater since Mr Craig resigned.
"There is no dirty politics campaign against Colin Craig," he said.
"I've certainly not been part of one."
Mr Stringer has been critical of Mr Craig within the Conservatives and attempted to have the former leader's membership cancelled by an interim board.
He assumed the role of party chairman after the mass resignation of board members last month, but was told by other party members that he had been suspended for breaching the party's code of conduct.
