A Moscow court on Friday slapped Google with an unprecedented fine of nearly $100 million, while Meta (formerly Facebook) received a fine of $27 million.
In recent years Russia has been piling pressure on Western social media giants, with President Vladimir Putin saying those companies were becoming as influential as elected governments.
Moscow has repeatedly taken legal action against them for allegedly not moderating their content properly and interfering in the country's affairs.
But so far fines on Facebook parent company Meta and Google have stretched into the tens of millions of rubles, not billions.
However on Friday a Moscow court fined Google a record 7.2 billion rubles ($98 million), while Meta (formerly Facebook) received a fine of 1.9 billion rubles ($27 million) for repeatedly failing to delete illegal content.
"For the first time, a Russian court has imposed fines that make up a share of the annual revenue of these companies in Russia," Russia's state communications regulator Roskomnadzor said in a statement.
The regulator said that Google and Meta had "ignored multiple demands" to remove materials that incite religious hatred and promote views of "extremist and terrorist organisations", among other violations.
Over the past few years, the Russian government has used the pretext of protecting minors and fighting extremism to crack down on dissent and control the Russian segment of the web.
It has also begun developing a so-called sovereign internet that can operate independently.
Kremlin critics have accused authorities of muzzling independent media, saying now the government is zeroing in on the internet, considered the last bastion of free speech in Russia.
The Western media giants have denied any violations in the past.
"We'll study the court documents and then decide on next steps," Google's press service told AFP on Friday. There was no immediate comment from Meta.
On Thursday, Twitter was handed its latest fine of three million rubles ($40,000) after authorities started throttling its services in the spring.
- Fines and threats -
Ahead of parliamentary elections in September, Russia's media watchdog blocked dozes of websites linked to jailed Kremlin critic Alexei Navalny, whose organisations have been outlawed in Russia as "extremist".
The regulator also ordered Google and Apple to remove an app dedicated to Navalny's "Smart Voting" campaign which advised supporters who to vote for to unseat Kremlin-aligned politicians.
The Silicon Valley giants complied, with sources telling AFP the decisions came after authorities threatened to arrest local staff.
Russia's media regulator has also blocked dozens of websites linked to Navalny.
During protests in support of Navalny last winter, Russian authorities accused platforms including Google's YouTube and Twitter of meddling in Russia's domestic affairs by not deleting posts calling for people to join the rallies.
Putin at the time complained that large technology companies were competing with states.
Russia has already blocked a number of websites that have refused to cooperate with authorities, such as the video platform Dailymotion and LinkedIn.
As part of broad efforts to bend foreign social media under its control, Russia in September banned six major VPN providers including Nord VPN and Express VPN.
Russia also introduced a new law demanding that smartphones, computers and other gadgets sold in the country come with pre-installed domestic software and apps.