The driver, Maurice Robinson, also pleaded guilty to acquiring criminal property but was not asked to enter a plea on 41 other charges including 39 counts of manslaughter in a case which has shone a light on the illicit human smuggling trade.
Robinson, 25, from the British province of Northern Ireland, was addressing a London court hearing from prison a month after the 39 bodies were found in the truck on an industrial estate in Grays, about 20 miles east of London.
Thirty-one of the victims were men or boys, and eight were women. The oldest was 44 and three were aged under 18, including two 15-year-old boys. Most were from Nghe An and Ha Tinh provinces in north-central Vietnam, where poor job prospects and other factors fuel migration.
Many impoverished people from Asia, the Middle East, and Africa make perilous journeys to western Europe in the hope of a better life, often after paying huge sums to criminal gangs.
Prosecutor William Emlyn Jones told Mondays hearing at Londons Old Bailey criminal court that it was likely to be a large and complex case.
Robinson admitted to having conspired with others between May 1, 2018 and Oct. 24 this year to commit an offense of assisting unlawful immigration, and to acquiring cash which he knew or suspected came from criminal conduct.
No trial date was set, and Robinson is next due in court on Dec. 13.