Rosell, his wife and four others, were accused of “large-scale money laundering” of close to €20 million ($23 million) since 2006, relating to television rights and sponsorship deals in Brazil.
The National Court, which handles major criminal cases, said it had acquitted all six accused because “after evaluating the evidence presented during the trial, the accusations were not proven”.
“As such, given the doubts that were raised, the principle of 'in dubio pro reo' must apply,” said the court, using the Latin for 'when in doubt favour the accused', referring to the presumption of innocence.
Prosecutors at the Madrid-based court had called for the ex-Barça boss, who was held in pre-trial between May 2017 and February 2019, to be jailed for six years.
The Rosells were accused of hiding money illegally obtained by Ricardo Teixeira, the former head of the Brazilian Football Confederation.
The case centres on a deal signed by Teixeira in 2006 with a company based in the Cayman Islands for the television rights to 24 Brazil friendly matches.
Altogether, Rosell and his wife allegedly received close to €15 million in their accounts as part of the deal.
They pocketed €6.6 million with 8.4 million destined for Teixeira, prosecutors say.
Rosell, 55, had previously lived and worked in Brazil, where he forged business links.
Teixeira has been indicted by US Justice Department prosecutors investigating the FIFA corruption scandal.
Rosell is also suspected of having received some five million euros illicitly as part of Nike's sponsorship deal with the Brazilian team.
He resigned as Barcelona president in 2014 over murky transfer dealings that brought Brazilian striker Neymar to the club from Santos.
Rosell is waiting to be tried in another case for corruption, fraud and tax evasion related to Neymar's transfer to the Catalan giants in 2013.