The former Scottish Labour leader said Stuart Campbell, who runs the pro-independence Wings Over Scotland website, had instructed his lawyers to try to have it overturned.
Speaking during an appearance at the Edinburgh Festival Fringe, she said he had “intimated to the courts” in the past few days that he intended to appeal Sheriff Nigel Ross's decision.
She also said the case had brought her “as close to a breakdown as I have ever been”, destroying her relationship with her father and shaking her trust in her party after it withdrew legal funding.
Mr Campbell took Ms Dugdale to court seeking damages of £25,000 after she criticised him in a newspaper column, claiming he was responsible for “homophobic Tweets”.
But in a written judgment handed down in April, Sheriff Ross said the MSP was protected by the principle of "fair comment" despite her claims being wrong.
He said that while the blogger was "not motivated by homophobia", he had only suffered “wounded feelings” and would only have been entitled to £100 of damages if he had won the case.
In an interview with the journalist Graham Spiers, Ms Dugdale insisted she had won the case “emphatically” on “every aspect of the law”. She added: “In the past few days, I’ve discovered that Wings Over Scotland has intimated to the court that he intends to appeal.
“So it’s going to come again. It’s going to go to the Court of Session and cost tens, if not hundreds of thousands of pounds again.”
She also said she thought her “entire world was caving in” when the Labour Party decided to withdraw its funding for her defence, worrying that she may end up losing her house.
“I was as close to a breakdown as I have ever been in my life, because I felt utterly alone,” she added.
Ms Dugdale also said her relationship with her father Jeff had ended after he publicly “cheered” for Mr Campbell during the case through his own Twitter account.
Mr Campbell later confirmed he would be launching an appeal.
"Kezia Dugdale brought the court case entirely on herself by defaming me with a false allegation and refusing to withdraw it when asked," he said.
"Her delaying tactics were solely responsible for both the fact that it dragged on for two years and for the astronomical costs.
"It's interesting that even although she now appears to grudgingly accept that I'm not a homophobe, she has failed to apologise for, or even publicly retract, her repeated smear to that effect, despite the sheriff finding unequivocally that it was entirely baseless and damaging."