Moscow City Court rejected band member Yekaterina Samutsevich's appeal to be considered an interested party in the case Wednesday, meaning a November decision banning four videos of the protest against Vladimir Putin now takes effect.
Internet providers face fines up to $3,000 if they don't block the footage.
Pussy Riot's videos were banned under Russia's vaguely defined "extremism" law, which is supposed to restrict neo-Nazi and terrorist groups. Critics accuse the Kremlin of exploiting the law to stifle opposition and free speech.
Pussy Riot shot to worldwide notoriety last year after three band members, including Samutsevich, were sentenced to two years in prison for 'hooliganism.' Samutsevich was later released on appeal.