Purpose. The article deals with the theoretical principles of competitiveness and its role in the development of entrepreneurial activity in the agrarian sector. Methodology / approach. Research of theoretical bases of formation and development of competitiveness of agricultural enterprises using the system approach made an opportunity to systematize scientific positions on the content and role of this phenomenon in entrepreneurial activity. Results. The essence and approaches to the understanding of competition as an economic phenomenon are determined. Arguments that the concept of «competitiveness» is closely linked to the notion of «competition», but in practical terms, such a connection corresponds to the essence of the market as a system of struggle for opposites. The theoretical model for defining the concept of «competitiveness» is that it is understood as a state of the subject of management by assessing the ability to productively realize its potential, obtaining from it benefits, profits sufficient for extended reproduction. Originality / scientific novelty. The theoretical descriptions of essence of competitiveness are with determination of her role and value in development of entrepreneurial activity in the agrarian sector, that consist in that a competitiveness is totality of qualities, properties, descriptions of subject (commodity, service, enterprise etc.), that provide possibility to satisfy necessities, and in entrepreneurial activity – to arrive at aims from development of production, promotion of products on the market, obtaining sufficient income. Practical value / implications. Research of theoretical principles of competitiveness and determination of her role in development of entrepreneurial activity will give an opportunity to the businessmen to revise the value of competitiveness.