Carlson published the conversation on X.
He argued that joining the war had cost Britain its empire, and suggested the country had also lost its self-respect.
Also, Carlson said the idea that Hitler "just randomly rolled into Poland" was a lie.
He argued that the Nazi leader had claimed that 15 percent of Poland’s territory had once been German and had been awarded to the country under the Treaty of Versailles.
A Polish news report noted that Carlson did not mention that the lands had a mixed population in terms of nationality and language, and had belonged to Poland in earlier centuries.
Rees-Mogg rejected the commentator's argument.
"I'm very surprised you're verging on defending Hitler," he said.
The former minister stressed that Britain had done what was necessary, and described the war as one of the few in history that was a straightforward struggle between good and evil.
Rees-Mogg said that without going to war, "we'd be speaking German". Carlson replied: "Who cares?"
The US commentator argued he was trying to assess the causes and consequences of the war objectively.
"I'm actually not a secret Nazi," he said.
Carlson hosted a prime-time show on Fox News from 2016 to 2023 and now broadcasts on social media.
He was a prominent supporter of Donald Trump and an influential figure in the MAGA movement.
In early April, President Trump criticised right-wing commentators who opposed the war against Iran, including Carlson, calling them "low IQ" and "losers."
The US journalist has interviewed Russian President Vladimir Putin and Foreign Minister Sergei Lavrov, and has been widely criticised for his pro-Russian views.
The Polish report described him as a "useful idiot" of Moscow.
Carlson recently said he plans to found a new political party, arguing that the United States is "a one-party state posing as a democracy."
(ał)
Source: tvp.info, interia.pl