Method and system for merchant acceptance of cryptocurrency via payment rails

A method for acceptance of blockchain payment at a traditional point of sale device direct to a merchant includes: receiving an authorization request for a fiat payment transaction including a transaction account number, transaction amount, and merchant identifier; identifying blockchain payment acceptance for a transaction account associated with the transaction account number; transmitting an address request to an exchange server including the merchant identifier; receiving a destination address associated with the merchant identifier for a blockchain network from the exchange server; transmitting a new blockchain transaction to a blockchain node in the blockchain network including the destination address and a cryptocurrency amount based on the transaction amount; and transmitting an authorization response for the fiat payment transaction to a payment network for routing to a point of sale device, the authorization response including an indication that clearance and settlement of the fiat payment transaction is not required.