Midfielder Franck Kessie, defender Andreas Christensen and forwards Robert Lewandowski and Raphinha are now available to face Rayo Vallecano, though Jules Kounde still needs clearance.
Barca had to meet LaLiga's salary cap to register their new signings but several "economic levers" including new investment deals released funding after the final lever was triggered.
Barcelona would have to free up so-called salary mass to register Kounde.
LaLiga restrictions also affected players who renewed deals in the close season but forward Ousmane Dembele and defensive midfielder Sergi Roberto have now also been registered.
Barcelona have been using several mechanisms to increase their revenue in order to offset losses, reduce debt and fulfil LaLiga's financial fair play rules.
The club said on Friday they had sold a 24.5% stake in their audiovisual studio to production company Orpheus Media for €100 million to raise funds.
Barca last month signed a deal with digital fan token firm Socios.com to sell 25% of their stake in Barca Studios.
