Five people were rescued, one passenger's body was found, but the remaining passengers were missing, the Ministry of Interior said in a statement on QNA.
The ship capsized about two miles off Doha's coast, local daily Gulf Times also reported, citing an Interior Ministry spokesman.
The paper said the majority of passengers worked for Doha-based HBK Power Cleaning, including 12 Nepalese and 11 Indians.
The ship belonged to Dubai-based Demas Marine, and provided support services to the oil industry, the paper said citing an HBK spokesman.