Abstract: This paper is mainly concerned with the application of countability theory in Finance. The author undertakes to explain countability theory for infinite countables not only in a precise manner but also gives analytical examples to simplify the theory even further. Some of the ways of ascertaining countability of infinite countables as indicated by the author entail: finding a bijection, finding a surjection, through a listing of elements and also through the determination of whether the elements are injective. The paper amalgamates Finance and countability by determining main areas in which the theory of countability is applicable in Finance. The paper explores: countability of Financial Statements constitutes, profit countability, countability of required rate of return, countability of company financing, countability in determination of capital investment decisions, countability in working capital constituents and countability in projection of financial statements’ data.