Although corporate valuation started to be implemented in 1980's it began to take its place newly in finance literature as a discipline. It is expected that the importance of corporate valuation will increase and corporate valuation be on the agenda of business community in the next years. Today, as the business world gets more complicated and business volume increases, new approaches are needed because of uncertainty in corporate valuation. The need for these approaches is even greater, especially with high investment expenditures, new technology, volatile cash flows and complex legal environments. New approaches will not eliminate this uncertainty, but they will form a basis for rational assessment in decision making. In this article, different analytical methods are discussed under the cash flow method, the valuation, the risk and the uncertainty in the valuation of the company and the use of the fuzzy set theory for the analysis under the uncertainty state is proposed. A model based on the triangular fuzzy number approach is proposed in the environment where there is not enough data for the model. Fuzzy set theory is a theory that completes the theory of probability under uncertainty in corporate valuation and should not be expected to give optimum results since it is based on uncertain data input. For this reason, the fuzzy set theory is a theory that can be used to obtain preliminary information in the first stage of corporate valuation. In summary, it is thought that the value of the company to be calculated by this theory will give an idea to the investor under uncertainty and will shed light on the valuation studies that the investor will perform in detail.