The two countries have not declared a formal military alliance, but Putin and Chinese President Xi Jinping signed a "no limits" partnership deal in 2022, less than three weeks before Putin sent his troops into Ukraine.
In May this year they agreed to deepen what they called their "comprehensive partnership and strategic co-operation" for a new era.
"We do not believe that China is pursuing an aggressive policy in the region," Putin said at the Valdai discussion club in the Russian Black Sea resort of Sochi.
He suggested that Taiwan was trying to stir up a Ukraine-style crisis in Asia in order to attract outside support.
China views democratically governed Taiwan as its own territory, despite strong objections by the government in Taipei, and regularly holds war games near the island.
"A lot is going on around Taiwan," Putin said.
"Everyone formally acknowledges, yes, Taiwan is part of China. But in reality? In reality, it is acting in a completely different direction. Provoking the situation towards escalation.
"We do support China. And because of this, we believe that (China) is conducting a completely reasonable policy. And also because it is our ally. We have a very large trade turnover, we co-operate in the security sector."
Taiwan's foreign ministry said China and Russia were the real problem.
"The regime of Russia's Putin launched a war of aggression against Ukraine, leading to misery for Ukraine's people and sanctions and condemnation from the international community," it said in a statement.
"China and Russia together continue to undermine the rule-based international order and have become a serious threat to world peace and stability."
Putin compared military drills between Russia and China to those the United States holds with Japan.
"These exercises do not threaten anyone," Putin said. "They are aimed at ensuring our security."
