Research firm Strategy Analytics said shipments in February fell by 38% year-on-year.
The outbreak of the coronavirus in China had a huge impact, report author Linda Sui said.
"Some Asian factories were unable to manufacture smartphones, while many consumers were unable or unwilling to visit retail stores and buy new devices," she said.
The report said that smartphone shipments dropped from 99.2 million in February 2019 to 61.8 million in February 2020.
