She added that Moscow now had to expand its goal of “demilitarisation” to cover Nato countries.
On Monday’s edition of her programme 60 Minutes, Ms Skabeyeva said: “It's time to admit, perhaps, that Russia's special operation in Ukraine is now over in the sense that a real war has started, World War III.
“We are being forced to demilitarise, not just Ukraine but Nato as a whole.”
She said the use of American M777 howitzers by Ukrainian troops in the Donbas had led her to the conclusion – though it was not the first time she has heeded the beginning of a third world war.
Ms Skabeyeva is a popular propagandist who enthusiastically follows the Kremlin line in broadcasts on Russia's second-most watched news network.
She previously claimed World War III had begun around six weeks ago after the sinking of the Russian warship Moskva in the Black Sea. Her claim at that time was also borne of Ukraine’s use of western military equipment.
She said: “One can safely say this has escalated into World War III, that’s for sure.
“Right now we are definitely fighting against Nato infrastructure, if not Nato itself. We need to recognise that.”
Her broadcasts on Rossiya 1 have often featured Russian officials, military and political, making unusual claims.
Most recently, senior Russian MP Oleg Morozov suggested the Kremlin kidnap a Nato defence minister and bring them to Moscow to be interrogated over any potential western military orders to Kyiv.
In comments to American news outlet Business Insider for a profile of Ms Skabeyeva, Russian media researcher Vasily Gatov said the broadcaster’s over-the-top and outrageous presenting style could be likened to American Fox News host Tucker Carlson in how it appeals to viewers.
“She is, to some extent, very similar to Carlson’s popularity. A controversial, scandalous person who polarises,” Mr Gatov said.
Unlike Mr Carlson, however, Ms Skabeyeva is paid by her country’s government to follow the state line.
An investigation last year by leading Kremlin critic Alexei Navalny’s Anti-Corruption Network found Ms Skabeyeva and her husband and co-host Yevgeny Popov, also a Rossiya 1 host, owned 300m rubles (£4m) of Moscow property.
A 2020 report by independent Russian news site The Insider said the husband and wife presenting team were among the highest-paid television propagandists in the country, earning 12.9m and 12.8m roubles (around £160,000) respectively – more than Russian defence minister Sergei Shoigu.