"Transportation of Russian gas through the territory of Austria is resuming," Gazprom said, adding that a "solution" was found with Italian buyers following regulatory changes in Austria.
Most Russian gas delivered to Italy passes via Ukraine through the Trans Austria Gas Pipeline (TAG), to Tarvisio in northern Italy on the border with Austria.
Italian energy company Eni said Wednesday that "gas supplies from Gazprom resumed today" and welcomed the "resolution by Eni and the parties concerned of the constraints resulting from the new regulations introduced by" Austria.
On Saturday, Gazprom suspended gas deliveries to Italy, blaming a transport problem in Austria.
"The reason is related to the regulatory changes that took place in Austria at the end of September," Gazprom said at the time.
In Austria, regulatory authority E-Control said the new rules, which entered into force on Saturday, had been "known to all market actors for months".
It said it expected "all to conform and take the necessary measures to fulfil their obligations".
The problems were linked to "contractual details" linked to the transit of gas towards Italy, E-Control said on Twitter.
On Monday, Eni said it was ready to pay a 20-million-euro guarantee to restart deliveries of Russian gas through Austria.
Following Wednesday's announcement, AFP asked Eni if such a payment had been made, but did not receive an answer.
Before the conflict in Ukraine, Italy imported 95 percent of the gas it consumes -- about 45 percent of which came from Russia.