For the first time Yulia Smirnova was allowed to visit Leonid Razvozzhayev, an activist with the Left Front movement, in the Matrosskaya Tishina prison since his detention eight months ago, his lawyer added Wednesday.
Razvozzhayev faces up to 10 years in prison if convicted of involvement in organizing riots at the May 2012 protest in Moscow on the eve of President Vladimir Putin's inauguration for his third term, which saw clashes erupt between police and protesters.
He has been also charged with illegally crossing the country's border with Ukraine to evade prosecution.
Razvozzhayev has refused to testify and pleaded not guilty to all charges against him.
Razvozzhayev fled Russia and was put on the federal wanted list after the pro-Kremlin NTV channel aired footage last October claiming to show opposition activists meeting with an influential Georgian politician, Givi Targamadze, allegedly plotting to destabilize Russia.
He also made international headlines last October when he claimed to have been abducted in Kiev by Russian security forces and tortured into giving a confession that he later retracted.
A total of 12 protesters are standing trial over the violence at the May 2012 protest on Moscow's Bolotnaya Square, with dozens more prosecutions expected.
The clashes were a pivotal moment for the opposition movement, whose mass demonstrations following the Russian parliamentary and presidential elections had previously not been accompanied by major violence and had not been broken up by the police.
Opposition activists accuse the police of provoking the violence, and claim the charges brought in relation to the protest are politically motivated.