King, 29, was unanimously convicted of sexual assault and causing actual bodily harm by a jury at London's Southwark Crown Court. Wigan later said his club contract would be terminated.
The court heard how King, who was celebrating his wife's pregnancy and scoring a winning goal only hours earlier, was repeatedly cold-shouldered by women revellers in London's packed Soho Revue Bar last December.
The court was told that when the slightly-built university student rejected his advances, King, a father-of-three, replied "I'm just out of your league. I'm a millionaire."
She replied: "I don't care who you are, take your multi-millions and get away from our table."
Prosecutors said he then lost his temper and in an outburst of "completely gratuitous violence" lashed out, "smashing" her to the floor.
His single clenched fist blow was so powerful that two other revellers -- one of them holding on to his arm -- were also sent flying, the Press Association reported.
As friends helped the 20-year-old to her feet, blood poured from her shattered nose, the court heard.
The Jamaican international from Waltham Cross, north of London, claimed he was a victim of mistaken identity.
But after hearing evidence from a string of witnesses, including a football coach who insisted King was the assailant, the jury decided he was lying.
The court later heard King had been in the dock seven times since the age of 17, accused of motoring offences and violence against women.
"You have shown not a hint of shame at your disgraceful and arrogant behaviour," said Judge Nicholas Loraine-Smith.
Referring to King's 35,000 pounds weekly wage packet and the fact his contract will be revoked costing him more than one million pounds, the judge added:
"I appreciate this will cost you an enormous amount of money, but it is difficult to be sympathetic when you were boasting about your earnings in the way you did."
Although King was on loan at Premier League club Hull City at the time of the incident, Wigan released a statement saying the player's contract would be terminated with due notice.
"He is absolutely sacked. We will not tolerate this kind of behaviour and as far as we are concerned he is finished football with Wigan Athletic," chairman Dave Whelan told Sky Sports.
"We have to follow the rules and regulations and we have given him 14 days' notice that his contract will be cancelled.
Wigan's added on their website (www.wiganlatics.co.uk): "Although the club was aware of the incident at the time, it was not aware of the severity, and therefore believe that the sentence received is justification for the player's actions."
The judge told the player in addition to the jail sentence, he would have to register as a sex offender for seven years.
As the sentence was read out, several of King's supporters stormed from court swearing at the judge.
One, pointing at the judge, screamed: "This is a clear case of institutional racism. You should not be up there. Up the National Front. Heil Hitler."
Another, referring to footballer Steven Gerrard's acquittal for affray, shouted: "Look at you. You are all white. Steven Gerrard is still walking the streets."
Liverpool captain and England midfielder Gerrard was cleared in July of attacking a businessman in a fight over music being played in a bar last December.
King is the latest Premier League player to be jailed for violence on a night out.
In May 2008, Newcastle United midfielder Joey Barton was jailed for six months after admitting to beating up a teenager.
(Reporting by Stefano Ambrogi; Additional reporting by David Cutler and Tom Pilcher; Editing by Ed Osmond and Ken Ferris)