Blake Fielder-Civil, 26, joined in a “vicious and one-sided” assault on James King while high on cocaine and alcohol, the court heard.
The victim suffered a broken cheekbone and was so badly beaten that he needed metal plates fitted to his face.
Fielder-Civil and his friend Michael Brown, 40, who launched the attack, tried to scupper the trial with a £200,000 (€252,000) pay-off to King, the landlord of the Macbeth Pub in Hoxton, East London.
The plot was exposed when the two middlemen, Anthony Kelly and James Kennedy, approached a national newspaper trying to sell CCTV of the June 2006 assault.
Sentencing Fielder-Civil to 27 months in prison at Snaresbrook Crown Court, Judge David Radford said he had behaved in a “gratuitous, cowardly and disgraceful way” by kicking King, 26, when he was lying prone.
He rejected arguments from Fielder-Civil’s lawyer, Jeremy Dein, that he should be released into drug rehab and said the seriousness of the beating merited an immediate custodial sentence.
Fielder-Civil, wearing a grey jacket and black shirt, is likely to be released in early December as he has already served nine months. He smiled at family and friends as he was led down.
The court heard the journalist who exposed the planned cover-up was told the money for the pay-off was to come from Winehouse.
Jocelyn Ledwood, prosecuting, said Fielder-Civil received a text message before the trial which read: “What happened at court? We were thinking about getting Amy to pay that silly c*** off.”
When police arrested Fielder-Civil last November they found him with nearly £2,000, and also £3,000 in his wife’s handbag.
Mr Dein told the court Fielder-Civil had been a drug user for half his life and his actions were the result of a “drugs-ridden lapse of judgment”.
He said Fielder-Civil was “befuddled” by heroin and cocaine use and was now trying to stay clean so he could be a “role model” for Winehouse, he said.
He said the couple wanted to stay together to kick their habit.
“It’s their ambition to divorce themselves from hard drugs not to separate themselves from each other.”