Three men, one Irish and two Northern Irish, have also been charged in relation to the incident.
The deaths shone a spotlight on the illicit global trade that sends the poor of Asia, Africa and the Middle East on perilous journeys to the West.
The defendants, aged between 24 and 36, were found guilty of "organising and brokering illegal emigration", after a one-day trial in the central province of Ha Tinh, Pham Van Thin, the father of one of the victims, told Reuters.
The victims, who included two 15-year-old boys, were mostly from Ha Tinh and its neighbouring Nghe An province, where poor job prospects, encouragement by authorities, smuggling gangs and environmental issues have fuelled migration.
They were discovered last October in a container at the back of a truck on an industrial estate in Grays in Essex, about 30 km east of London.
A police statement said earlier on Monday the defendants arranged for Pham Thi Tra My, whose desperate text messages sent from inside the container first alerted the world to the victims' plight, to travel illegally to France and then to Britain for $22,000 (€18,500).
My (26) was found dead with the 38 other victims in the container.
"I honestly don't want the defendants to face long prison sentences as I know that it was just an accident," said Mr Thin, Tra My's father, who attended the trial.
"Handing them long prison terms won't help me get back my daughter," Mr Thin said.
Last month, a 40-year-old Irish haulier, Ronan Hughes, became the second man to plead guilty over his involvement in the case. The other was Maurice Robinson from Northern Ireland, who was driving the truck when the bodies were found.
A third man, Eamonn Harrison, 23, also from Northern Ireland, pleaded not guilty to the same charges. A trial is due to begin on October 5th. -Reuters
