Herdade Lokua, 34, and Jospin Mujangi, 32, of Kinshasa, Democratic Republic of Congo, were arrested in November last year outside of Seattle.
Then, a federal grand jury indicted them for conspiracy, money laundering, smuggling and legal violations for the trafficking.
"In pleading guilty, both defendants admitted that beginning in November 2019, they agreed to smuggle elephant ivory, white rhinoceros horn and pangolin scales to the United States," the Justice Department said in a statement.
They worked with a middleman to negotiate the sales and coordinate imports to Seattle, the Justice Department said, adding that between August 2020 and September 2020, Lokua and Mujangi shipped three packages containing about 49 pounds (22 kg) of ivory from Kinshasa.
The World Wildlife Organization says the meat of the pangolin, often known as the "scaly anteater," is considered a delicacy and their scales are used in traditional Chinese medicine, making them among the most-trafficked mammal in the world.
Reuters could not immediately contact the representatives of Lokua and Mujangi.