Joy invented the Miracle Mop, a self-wringing mop made of a continuous loop of 300 feet (90 m) of cotton yarn. This invention was inspired by her frustration with traditional mops and the need for a more efficient and user-friendly cleaning tool. The mop's design allowed users to wring it out without getting their hands wet.

Initially, Joy struggled to market the Miracle Mop. She invested her savings and used her personal credit cards to produce the first batch of mops. She sold them at local trade shows and flea markets. Her initial investment totaled around $100,000.

Joy's breakthrough came when she appeared on QVC (Quality Value Convenience), a home shopping television network. She insisted on selling the Miracle Mop herself, and her passionate and authentic presentation resulted in the sale of over 18,000 mops in under an hour. This marked a turning point for her business.

Following her QVC success, Joy founded Ingenious Designs, LLC, the company through which she marketed and sold her inventions. The Miracle Mop became a household name, generating millions of dollars in sales. She expanded her product line to include other innovative household items.

Mangano sold Ingenious Designs to USA Networks (later known as IAC/InterActiveCorp) in 1999. However, she remained with the company and continued to develop and market new products through QVC. This allowed her to leverage the resources and reach of a larger corporation.

Joy continued to invent and market new products on QVC, including Huggable Hangers (velvet hangers designed to prevent clothes from slipping), Forever Fragrant (odor neutralizers), and Performance Platforms (shoe inserts). She became one of QVC's most successful and recognizable personalities.