Zac Mitchell, 20, was injured in April while working on a remote farming property in Western Australia.
"A bull kicked my hand into the fence," Mr Mitchell said of the incident.
He underwent two unsuccessful operations to reattach his thumb before doctors opted to relocate his big toe in surgery lasting eight hours.
Mr Mitchell said fellow workers had attempted to preserve his thumb immediately after the accident.
"They put it in the esky [cooler] with some ice," he told the BBC.