Both sides said they would collaborate on industrial parks in each other's countries, explore joint investment opportunities, broaden the use of local currencies in trade and also hope to work together on rail and university projects.
Xi said China also wants closer cooperation with Malaysia in areas such as defense, naval and military exchanges, security, law enforcement and combating terrorism and transnational crime.
Najib said he plans to visit China next year. He said he had "great confidence that under (Xi's) leadership, China will continue to make much progress and become an economic powerhouse and a major force in providing momentum for global economic growth."
In a subsequent speech to business leaders in Kuala Lumpur, Xi called for closer regional cooperation to ensure sustainable growth and said that "going forward, ASEAN will continue to be the primary choice for China as it opens up its economy."
He added that China remains "committed to reforms and economic restructuring" to sustain its growth.
Xi traveled to Kuala Lumpur on Thursday after visiting Indonesia's capital and is also scheduled to attend the Asia-Pacific Economic Cooperation summit in Bali.