Freesolo has represented artists such as Avril Lavigne, Gavin DeGraw, The Struts, Jazmin Bean, Hailee Steinfeld, Jharrel Jerome, Rachel Platten and Pitbull.

He was the founder, CEO, and President of A&M Octone Records, which signed and developed platinum artists including Maroon 5, K'naan Hollywood Undead and Flyleaf.

[18][19] In 2000, Diener founded Octone Records, while simultaneously serving as Senior Vice President of A&R Marketing[20] for Clive Davis[21] and the RCA Music Group.

[20] Upon Octone's original launch, Diener raised $5 million of private equity investment from BlackRock,[23][24] The Blackstone Group,[25] Lazard Freres, Credit Suisse First Boston, MacAndrews & Forbes, Kelso & Company and Soros Fund Management.

Prior to Octone Records and RCA Music Group, Diener was Vice President of A&R and Marketing at Columbia Records,[26] working with Aerosmith, Bruce Springsteen, Bob Dylan, Pink Floyd, Johnny Cash, Roger Waters, Black Crowes, New Kids On The Block, Iron Maiden, The Jayhawks, Tony Bennett, Jesse Malin, D Generation, Clutch, Chris Whitley and Terence Trent D'Arby, among others.