The ITC determination means that duties ranging from 96.3 percent to 176.2 percent previously announced by the U.S. Commerce Department would be put in place for five years.
The department said last month the products were being subsidized and dumped in the U.S. market.
The decision marked the first time that final duties were issued in a trade remedy case initiated by the U.S. government since 1985. Usually, trade cases are launched based on a complaint from a U.S. producer or group of producers.
The Trump administration has promised a more aggressive approach to trade enforcement by having the department launch more anti-dumping and anti-subsidy cases on behalf of private industry.
The National Marine Manufacturers Association, a trade organization for the North American recreational boating industry, criticized the decision and urged the administration to "to back off their tariffs first trade policy."
"Boat builders are seeing a 30 to 40 percent price increase for aluminum sheet, even though the vast majority source the material domestically. In addition, the compounding tariffs on Chinese aluminum sheet have strained the global supply, making it difficult for our industry to find enough aluminum sheet to keep up with manufacturing demand," it said.
In 2017, imports of common alloy aluminum sheet from China were valued at an estimated $900 million. The flat-rolled product is used in transportation, building and construction, infrastructure, electrical and marine applications.
U.S. aluminum industry firms, including Aleris Co, Arconic Inc and Constellium, testified in the case last year about what they termed a surge in "low-priced, unfairly traded imports."
(Reporting by Timothy Ahmann; Editing by Mohammad Zargham and Tom Brown)