The two men, who held talks in Beijing, have increasingly stressed their shared outlook which mirrors the 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.
“No matter the changes on the global arena, we should stick to the chosen path to expand and strengthen our comprehensive mutually fruitful cooperation.”
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 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.
Moscow faces harsh Western criticism and sanctions over its seizure of Crimea and the conflict in eastern Ukraine, which could see Europe reduce its consumption of Russian gas.
China also has tense relationships over territorial disputes with neighbours such as Japan, Vietnam and the Philippines.
Under Xi, Communist China has mounted crackdowns on dissidents and tightened limits on expression, while critics accuse Putin’s Russia of rights abuses.
China 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 for the China-Russia East Route pipeline, said to be worth $400 billion, during a visit to China by Putin in May.
On Sunday they stepped up the engagement, signing a memorandum of understanding to develop a second route to supply China with Russian natural gas, dubbed the “western” route.
The agreement could lead to a deal which would see China potentially becoming the biggest consumer of gas from Russia, overtaking Europe.
Alexei Miller, head of gas giant Gazprom, told Russian state television: “Gas deliveries along the western route will be flowing from fields in West Siberia, the resource base that we use now for delivering gas to Europe. This project will help us diversify gas supply from our traditional gas producing regions.”
Russia’s Rosneft and China National Petroleum Corporation (CNPC), both of them petroleum giants, also signed an agreement Sunday for the Chinese firm to take a 10 percent stake in a huge Siberian energy project.
CNPC also signed deals on gas supplies and transport routes. Banking agreements were also inked.
The two countries have carried out joint military exercises on land and sea and Kremlin spokesman Dmitry Peskov told reporters Sunday that “significant attention was dedicated to mutual transactions in all areas, including sensitive areas such as military and technical cooperation”.
China’s tightly-controlled yuan currency, which Beijing is looking to internationalise, also came up, with Peskov saying it was a “possible reserve currency in the region”.
Putin is visiting China for the Asia-Pacific Economic Cooperation (APEC) summit, which starts on Monday and will also be attended by US President Barack Obama, Japan’s Prime Minister Shinzo Abe and other leaders.
The APEC region includes 40 percent of the world’s population, nearly half its trade and more than half its GDP. -AFP