The 34-year-old, who was released by Scottish second division club Greenock Morton after being charged last year, entered his plea at Chelmsford Crown Court.
The NCA said Emmanuel-Thomas had recruited his girlfriend and another woman to travel to Thailand, where Emmanuel-Thomas briefly played in 2019, to collect the cannabis and smuggle it to Britain.
The two women were also charged with smuggling cannabis, but the prosecution offered no evidence against them and the charges were dropped on Wednesday, the NCA added.
Emmanuel-Thomas will be sentenced at a later date.
