The footage, which was captured by environmental campaign group Green Britain Foundation in July and August, shows one worker walking into a pen full of live turkeys before urinating.
Workers are also seen not following basic biosecurity practices, moving between sheds without changing boots or using foot dips, and throwing and mishandling birds.
A spokesman for Hockenhull Turkeys, which is owned by global company Aviagen Turkeys, said they were "appalled and very concerned" to see the secret filming which "does not represent the standards of animal husbandry and biosecurity we expect".
"High biosecurity and animal welfare standards are of the utmost importance to us and it is clear here that we have failed to live up to that promise," he said.
He added that the "vast majority" of staff "care deeply" for the animals in their care and that the footage "does not represent a typical day at Hockenhull".