Konstantin Malofeev, 45, an investment banker and media mogul close to the Kremlin, has been banned from entering Bulgaria for 10 years, chief prosecutor Sotir Tsatsarov told parliament.
The move follows a similar ban issued Tuesday against a former Russian intelligence officer, Leonid Reshetnikov - and espionage charges against the leader of Bulgaria's pro-Russia civil movement Rusofili, Nikolay Malinov.
The US Embassy in Sofia said in a statement late Tuesday that it was aware of the espionage investigation.
"The United States fully supports Bulgaria's efforts to defend its sovereignty from malign influence," the statement added.
Bulgarian Prime Minister Boyko Borissov said the probe was not targeting Moscow but stressed that "our geopolitical orientation... is the EU and NATO".
Bulgaria is a member of both the European Union and NATO.
Prosecutors say Malinov received funds from two Russia-based organisations - the Two-Headed Eagle and the Russian Institute for Strategic Studies (RISS) - to push through their interests in Bulgaria.