The contract - the value of which was not disclosed - was signed on the sidelines of World Nuclear Symposium in London on Thursday.
KHNP said it "anticipates that this contract will go beyond simply securing converted uranium and serve as an opportunity to expand cooperation in nuclear energy between South Korea and the United States. In particular, it is expected to serve as a foundation for further strengthening trust and cooperation between the two countries, as it coincides with the US government's nuclear power revitalisation policy, recent summit diplomacy between South Korea and the US, and the achievements of cooperation with Centrus".
The South Korean company noted the contract would also "establish a foundation for the safe storage and management of uranium raw materials in North America and secure the raw materials needed for future enriched uranium production at US facilities".
South Korea imports enriched uranium from countries including France, Russia and the UK, as under a nuclear energy agreement with the USA it is currently prohibited from enriching uranium or reprocessing used nuclear fuel within the country.
"This contract is expected to strengthen energy security by ensuring a stable supply of converted uranium, and will also serve as an opportunity to further solidify nuclear cooperation between Korea and the United States," said KHNP President Hwang Joo-ho.
ConverDyn is a joint venture between General Atomics and Honeywell, which provides uranium hexafluoride (UF6) conversion and related services to companies operating nuclear power plants in North America, Europe and Asia.