Jersey's Royal Court heard Polish national Pawel Dzielak slammed a knife with a 10-12cm (4-5in) blade onto a St Helier shop counter.
Dzielak, 32, left the shop with two mobiles phones and between £300-£400 which he spent on a hotel room, food, alcohol and cigarettes.
He had pleaded guilty to one count of robbery and threatening to use force.
The court heard Dzielak initially showed "no remorse" for the robbery that left shopkeeper Bruno Alves, of Temple Stores, in fear of his life.
Mr Alves told the court he had seen the defendant "acting suspiciously" outside his shop on the morning of the attack on 5 January.
That afternoon Dzielak went inside and threatened Mr Alves before taking the phones and the money.
The court heard Dzielak told a probation officer he had "got a buzz" from what he had done and he was "not sorry" for the robbery.
At his sentencing on Wednesday his defence advocate read out a letter of remorse from Dzeilak.
The court was told he had a high risk of reoffending and was a risk to the public because he has a history of mental health problems, was unemployed and suffering from depression.
Commissioner Julian Clyde Smith said in sentencing he had taken into account "aggravating factors" including the use of a weapon, how Dzielak had planned the attack and the impact on the victim and his family.
He recommended the defendant get treatment for his mental health problems and said, considering Dzielak had no ties to Jersey through accommodation, work or family, he should be deported.
A man who robbed a shopkeeper at knifepoint has been jailed for four years and recommended for deportation.