One of the people sentenced by the court was given a suspended death sentence - which in practice is normally commuted to life in jail - and two got life sentences, Yu said.
The vast majority of fentanyl used in the U.S.is imported, most of that coming from China.
A senior drug enforcement official, Yu Haibin, told reporters after the sentencing that China has worked closely with USA authorities to crack two other significant cases.
A year later, Mr Trump said Chinese President Xi Jinping had promised to stop fentanyl reaching the USA, but had not.
"After three months' hard work and tens of thousands miles of travel, China finally arrested more than 20 suspects and confiscated 11.9 kilograms of fentanyl, 19.1 kilograms of alprazolam and other drugs", the tabloid Global Times said in its report Thursday.
In December 2018, Beijing said it would reclassify fentanyl as a "controlled substance" following a meeting between Trump and Chinese President Xi Jinping on the sidelines of the G20 summit in Buenos Aires, Argentina.
Police stand guard outside the Xingtai Intermediate People's court in Xingtai, China's Hebei province, on November 7, 2019.
"As the success of the joint investigation demonstrates, Chinese and American investigators have the capacity to collaborate across worldwide borders", Austin Moore, an attache for the US Homeland Security Department in China, said at a press conference with Chinese officials following the sentencing. There are two other joint fentanyl cases ongoing, he said.
According to Austin Moore - a U.S. immigration and customs attache in China - the operation began in August 2017, when Homeland Security officers in New Orleans interviewed a "co-operating defendant".
Previously, the drug had overlooked law enforcement due in part to the ability of drug manufacturers to modify formulas and create fentanyl analogues that are not restricted by current Chinese law.
Nevertheless, Trump announced new tariffs on China over the summer as a response to what he saw as China s continued failure to stem the flow of fentanyl into the US.
Since then, the two countries have pledged to work together to combat drug proliferation, although Beijing has rejected responsibility for the United States addiction crisis.
Yu Haibin, deputy director of the Office of China National Narcotics Control Commission, on Thursday called allegations that Chinese supply is at the root of America's opioid problem "irresponsible and inconsistent with the actual facts".
However, Yu said accusations that China was the main source of the opioid in the United States were untrue. The Chinese government followed up with a statement that touted "China's willingness to sincerely and concretely cooperate" with the United States on drug enforcement.
According to the U.S. Centers for Disease Control and Prevention, more than 500,000 Americans died of drug overdoses in the decade ending in 2017 - increasingly, from synthetic opioids like the ones sold by the Xingtai network. Large amounts are often smuggled through Mexico, though Americans can also buy the drug online direct from Chinese labs, which then ship the product to the customer.