The tournament had been scheduled for June and July, but the change means it will now fall during the domestic season in Europe, from January 9 to February 6 next year.
"It (2021 Africa Cup of Nations) will be played in Cameroon from January 9 to February 6, 2021. Date changed for weather reasons at Cameroon's request," Fecafoot posted on Twitter.
The alteration means Premier League stars including Liverpool trio Sadio Mane, Mohamed Salah and Naby Keita, Manchester City’s Riyad Mahrez, and Arsenal pair Pierre-Emerick Aubameyang and Nicolas Pepe could be away from their clubs for around six weeks.
The tournament was played during the summer last year, with Mahrez’s Algeria beating Mane’s Senegal in the final.
The 2019 edition was the first time AFCON was not held during Europe’s domestic season, having originally moved to avoid such clashes.
However, “unfavourable climatic conditions” have seen Fecafoot reach an agreement with the Confederation of African Football (CAF).
"We have reviewed the period of the competition as requested by the Cameroonian party due to unfavourable climatic conditions during the period initially slated," CAF deputy general secretary Tony Baffoe said in a statement.
"After listening to the various arguments and viewpoints, and in particular from the Cameroonian meteorological authorities, the coaches and players; the representatives of the Afcon organising committee, which received the mandate from Caf Executive Committee to take the decision, has granted this request.
"A detailed reported shall be presented to the members of the Executive Committee during its next session on 6 February."