Outgoing Fifa president Sepp Blatter and Uefa president Michel Platini have both been handed eight-year bans from football activity. German judge Hans-Joachim Ecker, the head of Fifa's adjudicatory chamber, announced the decision on Monday.
The duo have been found guilty of breaking Fifa's code of conduct regarding a £1.3m ($2m) payment made to the Frenchman in 2011. Their suspensions are to begin immediately.
Blatter broke rules on conflicts of interest, breach of loyalty and offering gifts and benefits. Platini broke rules on conflict of interest and loyalty.
Blatter has already confirmed his plans to appeal the decision, telling a press conference: "I will fight for me and for Fifa."
A statement from Fifa read: "The adjudicatory chamber of the Ethics Committee chaired by Mr Hans-Joachim Eckert has banned Mr Joseph S Blatter, president of Fifa, for eight years and Mr Michel Platini, vice-president and a member of the Executive Committee of Fifa and president of Uefa, for eight years from all football-related activities on a national and international level."
Both have also received fines with Blatter ordered to pay £33,700 and Platini £54,000.
Both claimed the payment had been made in 2011 following a verbal agreement between the pair when the Frenchman worked for Blatter from 1998 to 2002. Their reasoning was rejected as "not convincing" by the ethics committee, however.
"The proceedings against Mr Michel Platini primarily related to a payment of CHF 2,000,000 (£1.34m) that he received in February 2011 from Fifa.
"The payment to Mr Platini had no legal basis in the written agreement signed between both officials on 25 August 1999.
"Mr Platini's assertion of an oral agreement was determined as not convincing and was rejected by the chamber."
The statement continued: "Mr Platini failed to act with complete credibility and integrity, showing unawareness of the importance of his duties and concomitant obligations and responsibilities.
"His actions did not show commitment to an ethical attitude, failing to respect all applicable laws and regulations as well as Fifa's regulatory framework to the extent applicable to him and demonstrating an abusive execution of his position as Vice-President of Fifa and member of the Fifa Executive Committee."
At 79, Blatter's ban effectively ends his career in football administration. Platini, 60, had been tipped to replace the Swiss as head of world football's governing body.
Both men have already serving a 90-day suspension when today's (Monday 21 December) decision was announced due to the ongoing investigation over a 2 million Swiss franc (£1.35m, $2.02m) payment by Fifa to Platini in 2011. Both men denied any wrongdoing.
Fifa's ethics committee is also still investigating the decisions to award the 2018 and 2022 World Cups to Russia and Qatar respectively.