The agreements are part of the flagship Belt and Road Initiative, China's vision of new trade routes described as a "21st century silk road".
Both countries also agreed to speed up the implementation of the China Myanmar Economic Corridor, a giant infrastructure scheme worth billions of dollars.
Xi's visit to Myanmar is the first of any Chinese leader in 19 years.
He hailed the meeting a "new era" of relations between the countries.
But analysts say Myanmar was generally cautious of investments by Beijing and was also being careful ahead of elections later this year.
China and Myanmar have historically had a fraught relationship, but have moved closer since 2017, when Myanmar was internationally condemned for its treatment of minority Rohingya Muslims in Rakhine state.
More than 730,000 Rohingya were forced to flee western Myanmar after a military crackdown that the United Nations has said was executed with "genocidal intent".
China has defended the country on the global stage and is viewed as the biggest obstacle to a prosecution of its leaders at an international war crimes tribunal.
