The Chelsea skipper had denied the charge but an FA independent regulatory commission ruled he was guilty of misconduct during the Barclays Premier League defeat at QPR on October 23 last year. He was also fined ?220,000, thought to be just over a week's wages.
Terry, 31, is considering an appeal, meanwhile questions have been asked why the ban imposed was only half the length of Liverpool's Luis Suarez, who served an eight-match suspension for racially abusing Manchester United's Patrice Evra.
Senior figures in football's anti-racism movements have privately queried the difference, but are unlikely to speak publicly until the appeals process is completed.
Joey Barton has also criticised the decision as "a shambles" compared to his own 12-game ban for violent conduct. He said on Twitter: "What an absolute farce. 12 games for violent conduct and only 4 for that. FA should be embarrassed shambles."
Terry expressed disappointment after the outcome, pointing out he was found not guilty in magistrates court in July of a racially-motivated public order offence in connection with the same incident.
Terry's representatives, Elite Management, said in a statement released on his behalf: "Mr Terry is disappointed that the FA Regulatory Commission has reached different conclusion to the clear not guilty verdict of a court of law. He has asked for the detailed written reasons of the decision and will consider them carefully before deciding whether to lodge an appeal."
Terry had been accused of calling Ferdinand a "f****** black c***" as an insult. He admitted using the words, but insisted he had only been repeating words he thought Ferdinand had accused him of saying.
The written reasons will also provide the explanation for the difference in length of ban compared to Suarez. The most likely outcome is that Terry only said the insult once, while Suarez was judged by his panel to have called Evra "negro" up to seven times. Suarez was also fined around a week's wages - in his case ?40,000.
Terry is likely to still be available to play for Chelsea against Arsenal on Saturday as the ban does not start until after the appeals process has been concluded. The defender has 14 days from the receipt of the written reasons for the decision, and if he does appeal then that hearing may not take place until the end of next month.
Source: PA
Source: PA