The leaders, who met on the sidelines of the Beijing 2022 Winter Olympics, agreed on a five-year plan for agricultural co-operation and identified key areas to grow and diversify trade and investment in the sector.
China is a major buyer of Argentine soybeans and beef.
It also has a major currency swap deal with the country, which helps to bolster its dwindling foreign reserves.
Fernandez is battling to revive the economy of Argentina, a major grains producer.
Argentina's government said in a statement that the two sides had highlighted the importance of the currency swap between their central banks and agreed to continue "strengthening co-operation" in this regard.
The two also signed a memorandum of understanding related to China's signature Belt and Road initiative, a platform for Chinese investment in railways, ports and highways worldwide.
"This strategic decision will allow the national government to sign different agreements that guarantee financing for investments and works for more than $US23.7 billion ($A33.5 billion)," Argentina's government said.
The Chinese side did not give such a figure.
In a 40-minute meeting, Xi and Fernandez agreed to work together and invest in areas such as green and sustainable development as well as digital economy.
China is willing to share development opportunities with Argentina and help it expand exports and upgrade its industries, China's foreign ministry quoted Xi as saying.
He was quoted as saying the two countries should deepen co-operation in trade, agriculture, energy and mining, infrastructure, investment and financing, anti-epidemic efforts, the digital economy, green development and other areas.
