Born in 1959 to a Jewish family, Ressler was one of five children born to Dorothy and Ira Ressler. His Father was an attorney and distinguished World War II veteran. Ressler graduated with a B.S.F.S. from Georgetown University’s School of Foreign Service and received an MBA from Columbia University’s Graduate School of Business. After school, he worked at Drexel Burnham Lambert eventually reaching Senior Vice President in the High Yield Bond Department with responsibility for the New Issue/Syndicate Desk.

In 1988, he married Actress Jami Gertz. They have three sons: Oliver Jordan Ressler (born 1992), Nicholas Simon Ressler (born 1995), and Theo Ressler (born 1998). Gertz-Ressler High Academy, a member of The Alliance for College-Ready Public Schools, is named after the couple. They are members of the Wilshire Boulevard Temple.

In 1990, on the heels of the collapse of Drexel Burnham Lambert, he co-founded the private equity firm Apollo Global Management with Leon Black, Drexel's managing Director, head of the Mergers & Acquisitions Group, and co-head of the Corporate Finance Department; John Hannan, Drexel's former co-director of international finance; Craig Cogut, a Lawyer who worked with Drexel's high-yield division in Los Angeles; Arthur Bilger, the former head of the Drexel's corporate Finance department; and Marc Rowan, Josh Harris and Michael Gross, all of whom worked under Black in the mergers and acquisitions department. In 1997, he co-founded Ares Management with former Apollo Global Management co-worker John H. Kissick and Bennett Rosenthal, who joined the group from the global leveraged Finance group at Merrill Lynch.

In 2005, he belonged to an investment group that made a successful bid led by Mark Attanasio to purchase Major League Baseball's Milwaukee Brewers.

In 2015, Ressler formed a group that includes former NBA player Grant Hill, Sarah Blakely, Jesse Itzler, Steven Price, and Rick Schnall, to purchase the Atlanta Hawks of the National Basketball Association.