Putin made the ironic remark a day after the US Justice Department charged two Russian media executives over an alleged illegal scheme to influence the November election with pro-Russian propaganda.
Before President Joe Biden withdrew from the race, Putin had said earlier this year - in another comment widely seen as not to be taken at face value - that he preferred Biden over Trump because the former was a more predictable "old school" politician.
President Vladimir Putin said he'll back Kamala Harris and her "infectious" laugh for US president. (AP PHOTO)
US intelligence agencies believe Moscow actually wants Trump to win because he is less committed to supporting Ukraine in the war against Russia.
Asked how he viewed the election now, Putin told an economic forum in Russia's far east that it was the choice of the American people.
But he then added that as Biden had recommended his supporters to back Harris, "we will do the same, we will support her".
Putin and the moderator were both smiling as he made the remark, which drew applause from the audience.
Expanding on his view of Harris, Putin said: "She laughs so expressively and infectiously that it means that everything is fine with her."
US AG Merrick Garland and FBI Director Christopher Wray announced charges against two Russians. (EPA PHOTO)
He added that maybe this meant she would refrain from further sanctions against Russia. By contrast, Putin said that Trump, as president, had introduced more sanctions against Russia than anyone in the White House before him.
"Ultimately, the choice is up to the American people, and we will respect that choice," the Kremlin leader concluded.
US intelligence has determined that Russia ran a disinformation campaign to boost Trump's campaign against Hillary Clinton in the 2016 election and sought to undermine Clinton's.
The US is preparing to go to the polls on November 5. (EPA PHOTO)
The Kremlin has repeatedly denied meddling in US elections, though late Russian businessman Yevgeny Prigozhin, who founded the Wagner mercenary group and was accused by the US of running Russian "troll farms", boasted in 2022: "We have interfered, we are interfering and we will continue to interfere".
On Wednesday, the US Justice Department filed money-laundering charges against two employees of Russian state broadcaster RT for what was described as a scheme to hire a US company to produce online content to influence this year's election.
Moscow will target US media in response, Russian foreign ministry spokeswoman Maria Zakharova said on Thursday.Â
