The Apple Watch remained the market leader but it shipped just over one million units in the third quarter of 2016 (July - September).
During the same period in 2015, it shipped 3.9 million. Of the five leading brands, only Garmin showed growth but its figures remained low.
However, this was a period before new versions were released, experts said.
Nonetheless, it still suggests that consumer appetite is weak, said Jitesh Ubrani from IDC.
"It has become evident that, at present, smartwatches are not for everyone," he said.
"Having a clear purpose and use case is paramount, hence many vendors are focusing on fitness due to its simplicity."