Parkinson entered the AK Food Store, in Central Avenue, Peterborough, at about 12.20pm on April 10.
As the shopkeeper was unboxing items alone, Parkinson made his way through the shop towards him.
He pulled out an axe from a holdall bag and began waving it around and demanded the shop worker open the cash register and hand him money, while making threats to kill him.
The victim, a man in his 30s, initially backed off but after a moment he began fighting back in self-defence. Following a struggle, the shop worker managed to grab Parkinson's axe-wielding arm and drag him outside the shop. The victim was then able to shout to passing members of the public, alerting one man in a car who called police.
Officers arrived a short while later to find the victim had detained Parkinson himself and he was arrested.
Parkinson, of Tilton Court, Peterborough, admitted charges of attempted robbery and possession of an offensive weapon. He was sentenced at Cambridge Crown Court on Friday, September 4.
Detective Constable Tom Hunt said: "This was a violent attempt to rob money from an innocent shop worker.
"However, thanks to the victim’s outstanding bravery Parkinson was unsuccessful and was caught red-handed.
"I hope his time in prison gives him time to reflect on his dangerous behaviour."