The decision could stall Turkey's crypto market, which has gained momentum in recent months as investors joined the global rally in bitcoin, seeking to hedge against lira depreciation and inflation that topped 16% last month.
In a statement, the central bank said crypto assets were "neither subject to any regulation and supervision mechanisms nor a central regulatory authority", among other security risks.
BNY Mellon's investment was part of a $133 million funding round that also saw participation from hedge fund Coatue Management, investment firm Ribbit Capital, growth equity firm Stripes and SVB Capital.
Fireblocks has a presence in Europe, Asia and North America, with customers including banks, neobanks, exchanges, hedge funds and market makers.