The two men, who held talks in Beijing, have increasingly stressed their shared outlooks which mirror their countries' converging trade, investment and geopolitical interests.
The two sides signed a series of agreements to step up their multi-billion-dollar natural resources collaboration.
"Together we have carefully taken care of the tree of Russian-Chinese relations," Xi told Putin at the Diaoyutai state guesthouse in Beijing.
"Now fall (autumn) has set in, it's harvest time, it's time to gather fruit," he said.
Russia and China have been brought together by mutual geopolitical concerns, among them wariness of the United States.
The two countries often vote as a pair on the UN Security Council, where both hold a veto, sometimes in opposition to Western powers on issues such as Syria.
Putin said that Russian-Chinese cooperation was "very important for keeping the world within the framework of international law, to make it more stable, more predictable".
"Me and you have done a lot for this and I am sure we will continue to work in this manner in the future," he added.
Beijing also has tense relationships over territorial disputes with neighbours such as Japan, Vietnam and the Philippines.
At the same time, it is constantly on the lookout for resources to power its economic growth.
After a decade of negotiations, the countries signed a huge 30-year gas deal said to be worth USD 400 billion during a visit to China by Putin in May.
Today they stepped up the engagement, with Russia's Rosneft and China National Petroleum Corporation (CNPC), both of them petroleum giants, signing an agreement for the Chinese firm to take a 10 per cent stake in a huge Siberian energy project.
Putin is visiting China for the Asia-Pacific Economic Cooperation (APEC) summit, which starts tomorrow and will also be attended by US President Barack Obama and Japan's Prime Minister Shinzo Abe, as well as other leaders.