In 2011, while completing her MBA at Harvard, Lake founded Stitch Fix from her apartment, aiming to revolutionize the retail industry by combining technology and personal styling. The company went public in 2017, making her the youngest female founder to lead an initial public offering at that time.

Before achieving significant wealth, Katrina Lake's early career encompassed diverse experiences that shaped her entrepreneurial journey. Initially enrolled in a pre-med program at Stanford University, intending to follow her father's path into medicine, she developed a keen interest in economics and earned her bachelor's degree in the subject. Post-graduation, Lake worked at The Parthenon Group, a management consulting firm, and later at Leader Ventures, a venture capital firm, where she gained insights into business strategies and the startup ecosystem. These roles provided her with a solid foundation in business operations and an understanding of investment dynamics. Seeking to deepen her entrepreneurial knowledge, Lake pursued an MBA at Harvard Business School. It was during her time at Harvard that she conceived the idea for Stitch Fix, aiming to revolutionize the retail industry by combining technology with personalized styling.

​Katrina Lake's wealth accumulation is primarily attributed to her entrepreneurial success with Stitch Fix, the online personal styling service she founded in 2011. By leveraging data analytics and personalized customer experiences, Lake transformed Stitch Fix from a startup into a publicly traded company. In 2017, she became the youngest woman to lead a company through an initial public offering (IPO) at age 34, with Stitch Fix raising nearly $120 million on its first trading day. At that time, Lake held a 16.6% stake in the company. Her net worth has fluctuated over the years, influenced by the company's stock performance and her stock transactions. As of May 2021, estimates placed her net worth at approximately $170 million. Lake's strategic vision and leadership have been central to Stitch Fix's growth, directly impacting her personal financial success.​