Dean Healey, who's 23, from Brixton in south London, was found guilty of robbing 17-year-old Lee Staples last year.
The court heard that Healey and an accomplice punched the teenager on a street in Streatham, south London, and demanded his wallet and phone.
'More careful'
After his attacker was jailed, Lee said: "It's great it's all over. When I'm out I look over my shoulder a lot.