The two sides exchanged memoranda of understanding, letters and protocols covering 33 projects in the fields of information, industry, agriculture, security and the resettlement of internally displaced people in Myanmar's war-torn Kachin State, which borders China.
The agreements were signed after a morning meeting between Xi and Myanmar's leader, State Counselor Aung San Suu Kyi.
The most significant pact appeared to be a concession and shareholder's agreement for the Kyaukphyu Special Economic Zone on the Bay of Bengal. With a deep-water port, it is the terminus of the 1,700-kilometer- (1,055-mile-) long China-Myanmar Economic Corridor, a major link in Beijing's Belt and Road Initiative whose other end is in China's Yunnan province.
Other agreements covered separate projects related to the corridor plan, which includes oil and gas pipelines, and road and rail projects from southern China through various parts of Myanmar to Kyaukphyu.
The Belt and Road Initiative aims to build a network of railroads, highways, ports and other infrastructure connecting China with other points in Asia, Europe and Africa.
The Myanmar corridor provides China with a shortcut to the Indian Ocean, a major goal of Chinese strategic planners. An outlet to the Indian Ocean allows China's sizable oil and gas imports from the Persian Gulf to bypass going through the Strait of Malacca, and could conceivably serve a future military purpose.
Xi's visit nominally marked the 70th anniversary of the establishment of diplomatic relations between China and Myanmar. But it also firms up a relationship in which China exercises diplomatic and economic muscle to extend its influence in Southeast Asia.
The relationship follows the pattern established with Myanmar's previous, military-led governments, which were treated as pariahs and sanctioned by many Western nations because of their suppression of democracy and poor human rights records.
Beijing provided a willing and able alternative as an investor, trading partner and weapons supplier.
Suu Kyi's freely elected government, which came to power in 2016, was originally applauded for the democratic and economic reforms it began to implement. But it now draws widespread condemnation over its human rights record.
It is in a similar position to its military predecessors as it faces possible Western economic sanctions over the brutal counterinsurgency campaign waged by its security forces that drove more than 700,000 members of the country's Muslim Rohingya minority to flee for safety in neighboring Bangladesh.
Last month, a case charging Myanmar with genocide came before the International Court of Justice in the Netherlands.
China has defended Suu Kyi's government in forums such as the United Nations, and Myanmar has returned the favor by following Beijing's positions on issue such as China's claims over territory in the South China Sea.
China's backing goes beyond words, since as a top investor and trade partner with Myanmar it offer a safety net if Western nations do impose sanctions.
But many of Myanmar's citizens have long harbored suspicions over the intentions of its big northern neighbor, and Suu Kyi and her ruling National League for Democracy party could face accusations of selling out the country as they face a general election later this year.
Xi's arrival on Friday was greeted with dancing children and youths waving the national flags of both countries and cheering, "Long live China-Myanmar friendship" and "Health to President Xi."
As the Chinese leader departed for home Saturday afternoon, four Myanmar fighter jets gave his plane an escort.