Geiger was born in Englewood, New Jersey, and grew up in Stamford, Connecticut. He moved with his family to Palo Alto, California after his father, a Budapest, Hungary-born Holocaust survivor, accepted a job as a satellite communication engineer in Silicon Valley. When Geiger graduated from high school, he enrolled at the University of California, San Diego; while a student, he started a co-operative record store called "Assorted Vinyl", selling 12-inch dance remixes from bands like Echo & the Bunnymen and Japan, while also running the Student Events Committee. After promoting a series of concerts on campus, Geiger started his own concert promotion company, That Kid Presents. After booking King Crimson, B.B. King and Ian Hunter, amongst others, at UCSD, Geiger began working for San Diego promoter Mark Berman Attractions/Avalon Attractions. While there, Geiger promoted hundreds of shows in San Diego, and founded and launched Humphrey's By The Bay, a popular local venue. Additionally, Geiger dj'd at 91X, a groundbreaking alternative radio station. With a degree in management science and biology, Geiger moved to Los Angeles after college and began working as a booking agent for Regency Artists, developing their alternative music division. Geiger spent 7 years at Triad, booking such artists as the Pixies, the Smiths, the Cocteau Twins, New Order, and Jane's Addiction. He would go on to create the Lollapalooza Festival with Jane's Perry Farrell and veteran agent Don Muller. In its inaugural year, 1991, Lollapalooza triumphed at the box office, and also "revolutionized the concert industry, ushered in the alternative rock format,and galvanized a previously marginalized generation of outsiders." In 1991, Geiger left Triad to join Rick Rubin's American Recordings as Executive Vice President of A&R, Marketing and New Media. During his tenure at American, Rubin and Geiger bought UBL.com, one of the first online music directories, from a Caltech student. Geiger left American Recordings in 1996 to create ARTISTdirect with Muller; the company launched in January 1997 with the premise that "the Internet was going to radically reshape the music business, both from a distribution perspective as well as create new revenue streams that hadn't existed before." Geiger served as CEO and then Vice Chairman of ARTISTdirect until 2003. Under his auspices, ARTISTdirect signed more than 130 top recording artists to e-commerce agreements, and became one of the most highly trafficked music sites on the Web. ARTISTdirect also included a booking agency and two record labels. ARTISTdirect is credited as the first internet company designed to create a direct connection between musicians and fans, and was additionally noted for web development, e-commerce, and digital fan management. The company went public in March 2000, one week prior to the stock market crash of 2000. Geiger left ARTISTdirect in 2003 to join The William Morris Agency as a Senior Vice President in the music division. After William Morris merged with Endeavor to become WME, Geiger was named the head of the music division, overseeing the agency's worldwide music business. In his capacity at WME, Geiger is the agent for David Byrne, The Flaming Lips, Jack White, Lady Gaga, Nine Inch Nails, Ozzy Osbourne, Black Sabbath, Steve Martin, Tony Bennett, Pixies, Roger Waters, and Trent Reznor, among many others. He left WME in 2020. As of 2018, Geiger had appeared on the Billboard "Power 100" list for seven consecutive years. He has won numerous Pollstar Awards, including three for Agent of the Year, and is on the Board of Advisors for Topspin Media. He delivered the keynote address at MIDEM in 2014.