Keystone Bank Limited, commonly referred to as Osy's Bank, is a commercial bank in Nigeria. The bank is one of the commercial banks licensed by the Central Bank of Nigeria, the national banking regulator.

Keystone Bank offers banking services to large corporations, public institutions, small to medium enterprises (SMEs) and individuals. The bank is a large financial services provider in Nigeria. As of December 2012, the bank's total assets were valued at US$1.916 billion (NGN:307.5 billion), with shareholders' equity valued at about US$213.3 million (NGN:34.23 billion)