Cambridge Analytica pitched to work for Leave.EU ahead of the European Union referendum but was never hired, one of the Brexit campaign group's leaders said.
Leave.EU co-founder Richard Tice said CA had also attended a press launch as part of the "potential team" the campaign would have had if it won the official designation for the referendum contest.
But when Vote Leave was chosen as the official Brexit campaign, Leave.EU did not hire CA to carry out any work, he said.
"They pitched for some business, they quoted for some business, they were not hired because Leave.EU did not win the designation," Mr Tice told BBC Radio 4's Any Questions.
"As far as I'm aware they played no role at all - I'm told that they played no role in Vote Leave who used a different firm and Leave.EU didn't use them because we didn't win the designation.
"It's complete mischief-making, the idea that 17.4 million changed their decisions because of some profiling, using Facebook or other stuff, it's just demeaning to our intelligence."
He added: "I never had any meetings with them. I was at one press launch when they were there, where they were presented as part of a potential team if Leave.EU won the designation - we didn't.
"So as far as I'm concerned there was no involvement whatsoever. "
Former CA director Brittany Kaiser, who was photographed on a panel with Leave.EU in November 2015, claimed the firm misled the public and MPs about the amount of work it had done.
She told the Guardian the work with Leave.EU had involved analysis of data provided by Ukip and there were "at least six or seven meetings" with senior officials from the campaign.
Ms Kaiser said she felt she had lied by supporting CA's company line that it "did no paid or unpaid work" for Leave.EU.
"In my opinion I was lying," she said. "In my opinion I felt like we should say 'this is exactly what we did'."
As the Electoral Commission launched its investigation into Leave.EU's spending, Ms Kaiser said the firm's now-suspended boss Alexander Nix had told them the narrative should be that the firm and campaign did not end up working together.
She said that "when I first found out that we were going to say that we did zero work on it, I felt betrayed and lied to" because "I was continually told I could go along with the narrative that we did work on it".
She said: "I was like: the narrative should be that the work that we did was never paid for so Leave.EU, by not registering that we did that work, are the ones that should be in trouble. Not us for lying for their asses.
"Literally why should we make excuses for these people? Why? I'm so tired of making excuses for old white men."
The whistleblower who revealed CA harvested details of 50 million Facebook users will appear before MPs next week.
Christopher Wylie will give evidence to the Commons Digital, Culture, Media and Sport Committee on Tuesday, March 27.