Chelsea are free to sign new players in the January transfer window after a FIFA-imposed ban was reduced on appeal by the Court of Arbitration for Sport (CAS) on Friday.
The ban, imposed following violations in the recruitment of minors, was reduced from two transfer windows to one, which Chelsea already served in the summer.
A fine was also reduced from 600,000 Swiss francs ($607,000; £462,000) to half that amount by the Lausanne-based court.
A CAS statement said that Chelsea were guilty of violating rules related to the international transfer and registration of minors, "but for a significantly smaller number of players", concluding that they were only guilty of one third of the violations found by FIFA.
In addition, the breaches of other transfer rules "were found to be less serious than those attributed to Chelsea FC by FIFA".
The initial ban was announced by football's world governing body in February, but Chelsea had always denied wrongdoing.
It followed a FIFA probe into Chelsea's signing of foreign under-18 players, including the club's former forward Bertrand Traore, a Burkina Faso international who now plays for French Ligue 1 club Lyon.
Traore signed professional forms for Chelsea in 2013 at the age of 18 but was not registered until January the following year.
At first they appealed to FIFA who partially lifted the ban in April, although only for players under 16 who are not "international transfers and first registrations of foreign minor players".
That left Chelsea still unable to sign players over the age of 16 during the summer transfer window.
Chelsea had been eager to have the ban lifted at the time, or at least suspended pending an appeal, so they could be in a position to sign a replacement for Eden Hazard, who was sold to Real Madrid.
Nevertheless, in the absence of new recruits, new manager Frank Lampard has enjoyed success promoting several members of the club's highly regarded youth academy to the first team.
Centre-back Fikayo Tomori, midfielder Mason Mount and striker Tammy Abraham have all returned from loan spells to become regulars at Stamford Bridge, their form leading to England call-ups. Abraham is Chelsea's top scorer with 12 goals this season.
Young full-back Reece James has also broken into the first team, while USA winger Christian Pulisic remains the last new signing brought to the club after being signed from Borussia Dortmund for £58 million ($74 million) last January.
Chelsea are currently fourth in the Premier League ahead of Saturday's trip to Everton.