My article, “Performance-in-Business: Armi Ratia’s Marimekko”, examines what happens to artistic performance in the concept of arts-in-business. In theatre and artistic performance, artistic thinking has traditionally been considered primary over economic thinking, but in arts-in-business the goal has been economic. The concept of arts-in-business, created in the 2000s, involves the strategic use of artistic elements in business in order to develop the creativity, problem-solving abilities, and innovativeness of employees as well as the brand of the business company. I will analyze the use of theatre as part of two historical forms of arts-in-business, the Bauhaus movement in Germany from 1919 to 1933, and the 2000s concept of arts-in-business. Regarding the latter, I will draw meanings from Lotte Darso’s (2004), Giovanni Schiuma’s (2011), and Jon McKenzie’s (2001) research on performance in business. After initiating a dialogue between these two approaches, I will provide a new theory for arts-in-business and apply it to Marimekko’s business practice. McKenzie (2001), as well as other studies of arts-in-business in the 2000s, does not emphasize the role of the manager-as-an-artist. In this article, I claim that only if the manager initiates artistic practice and the arts are interrelated to the product, can the arts penetrate the whole enterprise because of the role of managers in making constitutive decisions for the business. I will argue that some managers are able to do this. Ratia’s Marimekko is my exemplary case. As the key concept of my new theory of performance-in-business I employ performance scholar Josette Féral’s (2002) cognitively-oriented theory of theatricality based on the concept of a cleft and its variants in other theories. In the last section of this article, I will examine the Finnish fashion design company, Marimekko, under the management of Armi Ratia, as a business that employs the theatricality of clefts.