Putin arrived at Russia's Hmeimim airbase in Latakia Province, a government stronghold, where he was welcomed by Syrian President Bashar al-Assad, AFP reported.
Putin said he had ordered Defense Minister Sergei Shoigu to start a partial withdrawal.
"I have taken a decision: a significant part of the Russian troop contingent located in Syria is returning home to Russia," he said in a televised speech to troops at the base.
In 2015, Russia staged airstrikes in support of Damascus, targeting both the Daesh terror group and other terrorists fighting government troops.
Putin said the troops had helped the Syrian Army crush the "most battle-ready group of international terrorists," apparently referring to Daesh.
"On the whole the task has been completed. And completed brilliantly."
Putin said last month that efforts to end the war were entering a "new stage" as the focus shifted from military action to political reforms.
He said both Hmeimim and Russia's naval facility in Tartus would continue to function and warned that Russia would repel any fresh attacks by terrorists.
"If terrorists rear their heads again we will inflict the blows that they have not seen yet," he said.
Putin thanked Russian troops for defending Russia from terrorism and helping Syria remain a "sovereign independent state".
He said the conflict proved that Russia's armed forces, including intelligence officers, pilots, sailors, special forces, military police, sappers and military advisers, were on top form, and he also praised the country's defense industry.
"Our homeland thanks you, my friends," he said. "Have a safe trip. I thank you for your service."
After his speech Putin inspected the troops who goose-stepped to the tune of a popular Soviet-era song about World War II.
The size of the Russian deployment in Syria is not known but independent Russian military expert Pavel Felgenhauer has told AFP that up to 10,000 troops and private contractors could have taken part in the conflict.
Putin had ruled out dispatching ground forces in Syria, making the air force the mainstay of Moscow's Syria campaign.
Around 40 Russian servicemen have reportedly been killed in Syria since Moscow's military action. The Kremlin has acknowledged some of those deaths.