Gazprom, the world's biggest natural gas company, did not say whether Miller would attend the talks in China, where the Kremlin said Putin would discuss Ukraine and expanding both energy and trade ties.
In Iran, Miller met Iran's First Vice President Mohammad Mokhber and Iranian Oil Minister Javad Owji, Gazprom said.
"A Gazprom delegation headed by Chairman of the Management Board Alexei Miller, is on a working visit to the Islamic Republic of Iran," it said.
Gazprom, which holds about 15% of global gas reserves and employs about 490,000 people, is one of Russia's most powerful companies - so powerful it was once known as a state within the state.
But Gazprom plunged to a net loss of 629 billion roubles ($6.9 billion) in 2023, its first annual loss in more than 20 years, amid dwindling gas trade with Europe, once its main sales market.
Gazprom's gas exports to Europe have fallen to post Soviet-lows amid political fallout from the war in Ukraine and as the major Nord Stream pipelines were damaged by mysterious blasts.
Russia has been in talks for years about building the Power of Siberia-2 pipeline to carry 50 billion cubic metres of natural gas a year from the Yamal region in northern Russia to China via Mongolia.
Its capacity would be almost as much as the now idle Nord Stream 1 pipeline under the Baltic Sea that was damaged by explosions in 2022.
