Khasheem Kiah Thomas and Zilvinus Vitkas were found guilty at Thames Magistrates' Court after Waltham Forest Council prosecuted them with the same powers used to enforce those who litter.
Both men were given 80 pounds fixed-penalty notices for their separate spitting incidents but were fined 300 pounds by the court as they failed to appear before it, The Times reported.
The East London council has been issuing on-the-spot 80 pound fines since February, but this was the first time that a case had reached the courts.
In July, the council launched a "Don't Mess with Waltham Forest" campaign, which addresses six forms of environmental crime: spitting, litter, urination, dog mess, cigarette butts and takeaway litter.
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The council said the important thing about the verdict was that the court endorsed its belief that "counts spitting as waste".
Councillor Clyde Loakes, the council's deputy leader and cabinet member for the environment, said he was "absolutely thrilled" that the courts had backed the authority's tough stance.
"It has recognised the huge groundswell of opinion that is firmly behind our initiative to put an end to this disgusting habit," he said.
"We made a decision to use the powers we have at our disposal to crack down on this most unsavoury behaviour," Loakes added.
He said the residents of Waltham Forest had made it "very clear" and that a clean borough was their priority.
"I have also been contacted by a number of other councils who were interested to understand our approach and adopt it themselves. I think now we have tested this in the courtroom and been successful, many of those councils will be following our lead. Spitters everywhere beware," he said.