The letter was read out at a gala dinner in Washington during which US Treasury Secretary Janet Yellen accused Beijing of "unfair economic practices".
US companies have long complained about what they see as an unjust business environment in China, with limited protection for intellectual property and preferential treatment afforded to domestic competitors.
But in Xi's letter, he insisted that China would "unswervingly promote high-level opening up to the outside world, and create a market-oriented, rule of law-based, internationalised business environment".
"Chinese modernisation will bring more opportunities to global enterprises including American ones," the letter continued, according to state broadcaster CCTV.
Yellen used her speech at the US-China Business Council's anniversary dinner to call for China to shift from a state-driven approach in economic policy, saying that the model can discourage investors.
She said her next trip to China as Treasury chief would include discussing "difficult areas of concern".
Tensions between China and the United States have soared in recent years over issues such as trade and security.
But in November, Xi met his US counterpart Joe Biden in San Francisco, a meeting that saw both sides restore military communications and agree to boost cooperation.
Xi's letter acknowledged the meeting, saying the two men had "reached important consensus" and that China was "willing to work with the United States in line with the principles of mutual respect, peaceful coexistence, and win-win cooperation".
"There is great potential, broad space and promising prospects for strengthening China-US trade cooperation," he wrote.
Related Links
Global Trade News
| Subscribe Free To Our Daily Newsletters |
| Subscribe Free To Our Daily Newsletters |
