Mandatory squeeze-out of minority shareholders by majority shareholders, without the need for their consent, is regulated by law. If the entity is not listed on a regulated market, the process of valuation of shares for minority shareholders becomes more important. The purpose of this article is to describe methods and methodology of valuation of a company for the purpose of mandatory buyout of minority shareholders. Scope of the article includes legal framework of squeeze-out and the premises and constraints of mandatory buyout. The empirical part presents methodology of equity valuation based on the example of company of ORLEN Capital Group. Results of valuation in the income-based and market-based approach were discussed. Sensitivity analysis of valuation was also performed.