Toronto Star reporter Daniel Dale would not comment on his suit that also names Vision TV, which aired the Ford interview, saying an article he wrote for his newspaper would have to stand.
"Enough is enough. I can't tolerate it. I won't tolerate it," Dale wrote.
"I'm asking Ford to immediately retract the false insinuation that I am a pedophile. I am also serving Vision TV, which twice broadcast Ford's vile and defamatory remarks...even though their interview was filmed days before it aired."
The notice also calls for Vision TV to apologize.
Ford said a day after the interview that he stood by "every word."
In the interview broadcast Monday, Ford told host Conrad Black that Dale had perpetrated the worst invasion of his privacy during a May 2012 incident.
"Daniel Dale is in my backyard taking pictures. I have little kids. He's taking pictures of little kids," Ford told the former media baron and convicted felon.
"I don't want to say that word but you start thinking what this guy is all about."
Dale maintains he was writing a story about a plot of public land adjacent to Ford's house that the mayor wanted to buy, so he went to take a look when the mayor emerged from his home to confront him.
The reporter said at no time did he ever take any photographs of the mayor's family, house or even his property — and a police investigation bore that out.
He said he was suing reluctantly, and only because Ford was repeating lies about what had actually happened.
He cited Ford's comments on the Washington-based "Sports Junkies" program on Thursday in which Ford said, "When you've got young kids, that freaked me right out."
The comments brought renewed attention to the "malicious and defamatory insinuation" that the reporter had some sort of "predatory interest in young children," Dale said, adding that he has received strong support.
"Dozens of people, including people personally harmed by pedophilia, have offered me a total of thousands of dollars in donations for my legal fees," Dale said.
The libel notice is the first step in the process of suing for defamation. If Ford refuses to apologize and withdraw the comments, Dale said, the mayor would have to be prepared to "repeat his lies under penalty of perjury" in a courtroom.
There was no immediate response from Ford or his lawyer to the libel notice.
On Tuesday, however, a defiant Ford refused to apologize to Dale or clarify his comments.
"I stand by my words, what I said with Conrad Black,'' an angry Ford told a news conference.
"I stand by every word I said."
ZoomerMedia, which owns Vision TV, posted a statement on the website for its radio station AM740.
"As there is now the threat of legal action, ZoomerMedia will not be making a statement until such time as we can consult with our attorneys to consider the allegations and determine next steps," the statement said.
Also late Thursday, Black told The Canadian Press that Dale was on thin ice with the action.
"If the Star goes to court with this turkey, they'll be killed," Black said in an email.
"They raised the pedophilia question; Ford didn't."
Black declined to discuss the matter further or elaborate on previous comments that Dale might have a case because it was now a legal action.
Deputy Mayor Norm Kelly, who has assumed most of the mayor's powers in light of the various scandals, has denounced Ford's comments as "beyond the pale" and called on him to apologize.