Federal authorities in Seattle are investigating Huawei Technologies Co. for allegedly stealing trade secrets from U.S. companies such as T-Mobile US Inc., according to a person familiar with the matter.

The investigation is tied to civil suits filed against the Chinese telecommunications giant, including a case in which a federal jury in Seattle in 2017 found Hauwei liable for the theft of T-Mobile’s robotic technology, said the person, who asked not to be named because the matter isn’t public.

The...