The security guard was delivering cash to Blackpool Pleasure Beach.
The incident took place at around 1.35pm on April 22 as cash was being delivered to the attraction at the Withnell Road entrance.
The security guard was approached by a man who made off with the cash security box.
During the incident, the guard received a minor stab wound to his back.
The empty cash box was later recovered in a bush on the Promenade.
The 28-year-old, of no fixed address, pleaded guilty to robbery, possession of a knife and possession of a class A drug.
Walker was handed five years for the robbery, 18 months for possession of a knife and three months in respect of the drugs.
His sentences will run concurrently.