QPR midfielder Joey Barton has been banned for 12 matches after his behaviour against Manchester City on the final day of the Barclays Premier League season "tarnished the image of football".
The Football Association confirmed an independent regulatory commission found Barton guilty of two counts of violent conduct on Wednesday.
The FA announced Barton received an automatic four-game suspension, with the additional eight matches a consequence of the manner of his dismissal. He was also fined £75,000.
Barton was shown a red card at the Etihad Stadium for elbowing Carlos Tevez, and he then kicked Sergio Aguero before attempting to headbutt Vincent Kompany.
The acts were condemned by the chairman of the regulatory commission, who stated: "There are rules of conduct that should be adhered to, and such behaviour tarnishes the image of football in this country, particularly as this match was the pinnacle of the domestic season and watched by millions around the globe."
QPR said they will now begin their own internal investigation.
Club spokesman Ian Taylor said on Twitter: "QPR will be making no comment in regard to the Joey Barton case. Internal investigation will begin in due course."
Barton denied the charge of violent conduct against Kompany but the FA said the case against Barton was found to be proved.
A Football Association statement said on Wednesday: "An independent regulatory commission has today dealt with two charges of violent conduct against Joey Barton, arising from the game against Manchester City, resulting in an eight-match suspension and £75,000 fine for the Queens Park Rangers midfielder.
"This eight-match suspension is to run consecutively to the four-game suspension Barton was already given for his dismissal in the fixture, making a total of 12 matches."
The FA's statement outlined the reasons behind Barton's long ban.
The statement said: "Following Barton's dismissal in the 54th minute of the match, there followed two incidents involving Manchester City's Sergio Aguero and Vincent Kompany. As Barton had already been dismissed, both of these incidents fell outside the jurisdiction of the referee.
"Barton accepted the charge of violent conduct against Aguero but denied the second breach of violent conduct against Kompany. The independent regulatory commission, however, found this second charge proved.
"Barton is already serving a four-match suspension for his dismissal in the match, which consists of three matches for violent conduct plus one match as this was the player's second dismissal of the season.
"The two further breaches for violent conduct ordered he be suspended for eight matches to run consecutively to the four matches, taking the total suspension to 12 matches."
The FA's regulatory panel had discretionary powers to further increase the length of the suspension if charges were found to be proven.
Barton's admission on Twitter that his violent actions were a cynical ploy to provoke a City player to be sent off saw those discretionary powers employed.
Barton insisted via Twitter on the day of his sending-off that he had not lost his head, but that a team-mate "suggested I should try to take 1 of theirs with me".
Speaking earlier this month, QPR chairman Tony Fernandes said: "There are experienced people who will come back to me and we'll review the whole situation.
"Joey has been an integral part of the club and has played his part.
"This is football, and I'm new to it. I don't profess to have all the answers."
Joey Barton Factfile:
1982: Born Huyton, Merseyside, September 2.
2003: April - Makes Manchester City debut in a 2-0 defeat at Bolton.
2004: February - Sent off at half-time in an FA Cup tie at Tottenham with his team 3-0 down. City go on to win 4-3.
April - Storms out of Eastlands before kick-off after being dropped from the side to face Southampton.
July - Criticised by manager Kevin Keegan for causing a mass brawl in a pre-season friendly at Doncaster.
December - Stubs lit cigar in the eye of young team-mate Jamie Tandy during City's Christmas party. Fined six weeks' wages by the club. Forced to pay four weeks' salary - approximately £60,000 - immediately, with a further two weeks suspended for a year. Tandy later sued Barton, winning £65,000 in damages.
2005: May - Barton breaks leg of 35-year-old pedestrian while driving his car at 2am in Liverpool city centre.
July 22 - Involved in an altercation with a 15-year-old Everton fan at City's team hotel in Bangkok, where the team are playing in the FA Premier League Trophy.
July 27 - Fined eight weeks' wages by City after being found guilty of gross misconduct in the Bangkok incident. Agrees to undertake a programme of rehabilitation.
2006: January 30 - Hands in a transfer request, which is rejected.
September 30 - Drops his shorts in direction of Everton fans following City's 1-1 draw at Goodison Park. Later charged by the Football Association over the incident and fined £2,000.
2007: February 7 - Makes senior England debut as a 78th-minute substitute against Spain.
May 1 - Suspended by City for the rest of the season after training-ground altercation with Ousmane Dabo.
June 14 - Completes £5.8million move to Newcastle.
August 2 - Charged with assault over Dabo incident.
October 4 - Appears in court charged with Dabo assault. Indicates he will plead not guilty.
October 22 - Makes Newcastle debut in 3-1 victory over Tottenham.
December 1 - Causes controversy by describing the St James' Park crowd as "vicious".
December 27 - Arrested in Liverpool city centre.
December 28 - Charged with common assault and affray and refused bail.
2008: January 3 - Released from custody after being granted bail.
May 20 - Admits assault and affray and is jailed for six months at Liverpool Crown Court.
July 1 - Receives four-month suspended sentence for assaulting Dabo.
July 28 - Released from prison.
July 31 - The FA charge Barton with violent conduct over the Dabo incident.
August 30 - Returns as a substitute for Newcastle away to Arsenal.
September 5 - Banned by the FA for 12 matches - six of which are suspended - and fined £25,000 after admitting violent conduct charge in relation to Dabo incident.
2009: May 3 - Sent off against Liverpool for late challenge on Xabi Alonso.
May 5 - Suspended until further notice by Newcastle.
November 11 - Charged with violent conduct by FA after allegedly punching Blackburn's Morten Gamst Pedersen during a league match.
2011: August 1 - Newcastle transfer-list Barton after a series of Twitter comments criticising the club, making him available on a free transfer.
August 26 - Signs for QPR on a four-year deal and is made club captain.
September 17 - Scores first QPR goal, but is also involved in a confrontation with Karl Henry, who he later criticises on Twitter.
2012: January 2 - Receives first red card for Rangers for butting Norwich's Bradley Johnson.
March 21 - Booed by QPR fans after a poor performance against Liverpool. Criticises his treatment on Twitter.
May 13 - Dismissed for striking Manchester City's Carlos Tevez on final day of season. He goes on to knee Sergio Aguero from behind, thrust his head toward Vincent Kompany and is restrained when attempting to confront Mario Balotelli.
May 14 - Charged with two acts of violent conduct by the Football Association following his actions against Manchester City.
May 16 - QPR announce an investigation into Barton's conduct in the game against City.
May 23 - FA announce an independent regulatory commission found Barton guilty of both violent conduct charges, resulting in a ban of 12 games and a fine of £75,000.