Scarborough, co-host of Morning Joe, said that Mr Barr should have been charged with perjuring himself when he was giving testimony to Congress.
The host's criticisms come on the heels of a recently declassified intelligence report that determined Russia attempted to undermine Joe Biden's campaign prior to the 2020 election, and that Iran attempted to do the same to Mr Trump.
However, it said there was no indication China attempted to interfere in the election, despite Mr Trump and his administration's insistence that the country had meddled.
"The lying and politicisation of intel was just breathtakingly dangerous," Scarborough said. "You have Bill Barr, [National Security Adviser Robert] O'Brien and [Director of National Intelligence John] Ratcliffe who all lied and said – this is Ratcliffe pre-election, quote – 'China is using a massive and sophisticated influence campaign.' He knew that was a lie, O'Brien knew that was a lie. Barr said, 'Oh, I looked at the intelligence,' and he lied through his teeth."
Mr Barr publicly equated China with Russia and Iran in terms of the threat level they posed to election security.
During an interview with Wolf Blitzer on CNN, Mr Barr said China was more of a risk than Russia, and when asked why he thought that, he justified his analysis by saying: "I've seen the intelligence."
Scarborough, a former Republican congressman who has been a scathing critic of Mr Trump, said the former attorney general had lied just to score political points with the then-president and help his chances in the 2020 election.
"The attorney general of the United States, going out of his way to lie through his teeth about intel, all for political purposes, all for political purposes," he said.
"Now we find out this week that not only were they being liars at the time, but you had people in the intel community who were nervous about the fact that they were going to use their work, go out, twist it out of its proper context, and start spreading lies for Donald Trump's re-election campaign – and that's what the attorney general and the head of the intel community and trump's national security adviser, all three, did. Deeply shameful, deeply dangerous."
The host openly wondered why Mr Barr was never held accountable for his alleged lies.
"He took the Mueller report, in the words of William Rehnquist, he wrenched their words from their proper context, he lied in front of the House and the Senate, committed perjury," Scarborough said. "I never really figured out why they didn't try to charge him for that."
Scarborough said Mr Barr was the worst attorney general to ever hold the position.
"He claims to have seen intelligence and lied about it, spread lies about what the intel community had found along with Ratcliffe and O'Brien, saying that China was basically trying to do the same thing that Russia was doing," he said.
"We found out that Iran was doing it. Why did they feel like they had to lie about China? Here's Bill Barr, again, Bill Barr again showing why he's the worst attorney general ever. John Mitchell looks like Atticus Finch compared to Bill Barr."