垄断性竞争（英语：Monopolistic competition），或称为独占性竞争，一种不完全竞争（Imperfect competition）市场的形式之一。最早由美国经济学家爱德华·钱柏林，在1933年的著作《垄断性竞争理论》（Theory of Monopolistic Competition）提出。

在垄断性竞争市场中，存在许多厂商供应者，类似于完全竞争市场，没有任何一个厂商可以独占市场。但它与完全竞争市场不同的地方是，在此种形式之下许多厂商制作与其他有些差异化的产品（意即，虽然这些公司的产品互有取代性，但是互有差异，例如在品牌，品质上仍有不同）。短期而言，属于独占性竞争的厂商就像是一个独占公司一般，可利用部分的独占市场力量 （Monopolistic market power）提高售价以获取比较高额利润。但是在长期而言，由于竞争者不断进入，产品的差异化优势因为竞争而逐渐缩小，市场慢慢变成为类似完美竞争 （Perfect competition），厂商就无法再获得过多的经济利益。但是在此之前，独占性竞争的公司通常保留部分产能。教科书经常举例说明的产业包括餐馆业，谷类加工食品业，服装业，鞋类业，以及大都会的服务业。

Monopolistic competition is a type of imperfect competition such that many producers sell products that are differentiated from one another (e.g. by branding or quality) and hence are not perfect substitutes. In monopolistic competition, a firm takes the prices charged by its rivals as given and ignores the impact of its own prices on the prices of other firms. In the presence of coercive government, monopolistic competition will fall into government-granted monopoly. Unlike perfect competition, the firm maintains spare capacity. Models of monopolistic competition are often used to model industries. Textbook examples of industries with market structures similar to monopolistic competition include restaurants, cereal, clothing, shoes, and service industries in large cities. The "founding father" of the theory of monopolistic competition is Edward Hastings Chamberlin, who wrote a pioneering book on the subject, Theory of Monopolistic Competition (1933). Joan Robinson published a book The Economics of Imperfect Competition with a comparable theme of distinguishing perfect from imperfect competition.