Federation Internationale de Football Association said Chelsea had been found to have "breached article 19 of its regulations in the case of 29 minor players and to have committed several other infringements relating to registration requirements for players".
Chelsea Football Club have been banned from signing players for two transfer windows after they were found guilty of breaching rules about signing minors by FIFA.
The club have been heavily fined and given a two-window ban, for breaching rules around the transfers of minors.
Fifa's basic rule is that clubs can not bring in players under 18 from other countries, unless their parents have emigrated for reasons not connected to football or both the player and club are based within 50km of a national border. One of the breaches is reported to be in relation to the signing of Bertrand Traore in 2013.
Chelsea have been given three days to appeal against FIFA's decision. However, as revealed by Federation Internationale de Football Association, the ban will still allow players to leave the club.
Late fashion designer, Karl Lagerfeld leaves $200m fortune to cat
The late fashion icon also announced Choupette would inherit some of his fortune in an interview with Numero magazine a year ago. Lagerfeld was looking after the cat while Giabiconi was travelling, but fell so in love that he refused to hand her back over.
The ban does not apply to the club's women's and futsal teams.
They have also been fined 600,000 Swiss Francs (£460,314).
The ban means Chelsea will be unable to sign players until the 2020 summer window but the London club are expected to appeal the sanction.
But the news is a body blow for Chelsea at a time when the manager, Maurizio Sarri, is clinging to his job, after a dismal sequence of results and having lost the confidence of the Stamford Bridge crowd, and the squad is in need of a make-over with doubts concerning the future of a host of players.
However, the club said numerous individual cases highlighted involved players on short-term trials who were not signed. "It was fined CHF 510,000 (£391,486) and given a period of six months to address the situation concerning the global transfer and first registration of minors in football", added the statement.