Browder, a British citizen who was born in the USA, claims the case against him is politically motivated.
'The Spanish authorities, with the encouragement of the British, should release Bill Browder.
Bill Browder, once the boss of late anti-corruption Russian lawyer Sergei Magnitsky, said he was arrested in Madrid.
Browder confirmed via Twitter that he was released after approximately an hour in custody, but his arrest in a European capital raised fears of Russian influence on foreign soil.
That question is of particular concern in Britain, where two British citizens, Sergei Skripal, an ex-Russian spy, and his daughter, Yulia, were targeted in a nerve agent attack in Salisbury on the afternoon of March 4.
Browder, who ran Hermitage Capital Management, was once among the most significant foreign investors in Russian Federation. But his mood changed when he was denied entry to the country in 2005.
Shortly before 11 a.m., Mr Browder tweeted a second photo of an English translation of his arrest warrant, dated May 30: "he/she has been arrested by his/her alleged participation in the criminal facts: fraud".
As early as July 2013, the global police organization said it erased from its database Russian requests to locate and arrest Browder due to its "predominantly political character".
It was not long before Browder hopped on a plane out of Spain and put the arrest in his rear view - but questions continue to eddy around why, exactly, the activist and commentator was arrested in the first place.
United Kingdom businessman William Browder, who is wanted by Moscow for tax evasion, said on Wednesday that he had been detained by the Spanish police on a Russian worldwide arrest warrant.
Browder asserted that his detainment came because Russian Federation had obtained an active Interpol Red Notice, or a formal request that one Interpol member country arrest a suspect based on a valid warrant issued by another member country. "The moment it was determined the search warrant was not valid, he was immediately released without any kind of interrogation", the spokesman added.
McAuley reported from Paris.