Sheffield Crown Court heard during a trial how Fahim Hersi, aged 22, of Broomhall, was stabbed in the car park at Cineworld, at Centertainment, in September, 2018.
Noel Ramsey, aged 22, of Nottingham Street, Burngreave, had denied murder but pleaded guilty to manslaughter on Tuesday, after admiting throughout to stabbing Fahim in self-defence.
Ramsey’s friend Layton Morris, aged 22, of Ferrars Road, Tinsley, had denied assisting Ramsey by disposing of the knife near a bin but he also pleaded guilty on Tuesday.
Ramsey received five years jail and Morris was handed six months in prison.
In a statement, Fahim's mother, Khadija, said: "I have lost my son and friend. The day he died is the day I died."
She described him as "extremely bright" with "so much to live for," but was "disappointed with the evidence given by Fahim's alleged friends."