[16] He grew up in Lafayette Hill, Pennsylvania, where he started a ski-tuning shop in his parents' basement when he was 12 and two years later, using $2,500 in bar mitzvah gifts as seed capital and a lease signed by his father, he opened a formal ski shop in Conshohocken, Pennsylvania, named Mike's Ski and Sport.

[16] Rubin agreed, continuing to operate the business, which grew to five ski shops before he entered college.

[16] Using the proceeds from his serendipitous overstock transaction and after selling his ski shops, he founded the athletic equipment closeout company KPR sports—named after his parents' initials—which bought and sold over-stock name brand merchandise.

[21] In 2019, it was announced on CNBC that Simon Property Group would team up with Rubin to take their mall inventory online, and contribute $280 million to the venture.

[26][27] At the onset of the COVID-19 pandemic in early 2020, Rubin shut down a Fanatics' MLB uniform manufacturing plant to generate hospital gowns and PPE for frontline workers.

[19] In August 2020, he secured $350 million Series E funding for Fanatics that raised the valuation of the company to $6.2 billion.

[36] Rubin was a member of the investment group that won a $280 million bid for the team led by Josh Harris and David Blitzer.

[40] In 2013, as a member of another investment group led by Harris and Blitzer, Rubin bought a share in the New Jersey Devils and the Prudential Center for $320 million.

[42][43] Rubin started the viral "ALL IN Challenge", which raised more than $60 million to fight food insecurity during the COVID-19 pandemic, with donations being made to charities including No Kid Hungry, Meals on Wheels, World Central Kitchen, and Feeding America.

He joined Mark Cuban, Barbara Corcoran, Lori Greiner, Robert Herjavec, Daymond John and Kevin O'Leary, as they continue their search to invest in the best up-and-coming businesses and products on the market.

[64][65][66][67][68][69] Rubin splits his time between the Philadelphia area, near where he grew up,[16][70] and New York City, where in 2018 it was reported that he purchased a $43.5 million penthouse.

[75] Since 2021, Rubin has hosted an annual "white party" at his $50 million estate in The Hamptons for Independence Day, attended by many athletes and celebrities including Jay-Z and Beyoncé, Justin Bieber, Tom Brady, and Kim Kardashian.

[82] Rubin was included in Bleacher Report's "Power 50" list in 2018, which highlights influential figures in sports culture.