President Donald Trump announced the tax soon after the market closed, after stocks plummeted due to his previous threats of raising taxes and canceling a meeting with Chinese President Xi Jinping later this month.
The Dow Jones Industrial Average fell nearly 900 points, and the S&P 500 fell 2.7% - the biggest one-day drop since April.
The new tax rate will take effect from November 1 "or sooner, depending on any further action or change by China," Mr. Trump wrote on the Truth Social platform.
According to the International Economic Institute Peterson, the average tax rate on imports from China is currently around 57%, after reaching its highest rate of 140% at the peak of the trade war that began earlier this year.
President Trump also stressed the need to impose export control measures on key software in retaliation for China's new measures against rare earth minerals.
This announcement could impact the US-China trade deal process, which businesses and investors hope will stabilize one of the world's most important foreign policy ties.
China has issued new export restrictions on rare earths and launched an antitrust investigation into US mobile chip giant Qualcomm a few weeks after launching an investigation targeting Nvidia, the US AI chip giant.
