[4] Klarberg has managed several prominent individuals including musician/actor Justin Timberlake,[5] recording artist Nicki Minaj, music group NSYNC,[6] artist Alec Monopoly, entrepreneur Russell Simmons,[7] DJ and record producer Kaskade, NASCAR champion Kyle Busch, DJ and record producer John Summit, professional tennis player/model Anna Kournikova,[1] NBA All-Star Kyle Lowry, MLB All-Star and Homerun Champion José Bautista, professional soccer player Jozy Altidore, NBA analyst and entrepreneur Jay Williams, MLS All-Star and Captain of the United States men's national soccer team Michael Bradley, and NHL Hall-of-Famer Mark Messier.

[12] He regularly appears on CNN, CNBC and The Wall Street Journal Report, and authored the book "Winning Tax Strategies and Planning for Athletes and Entertainers.

[13] In April 2016, Klarberg represented NFL star Rob Gronkowski and launched with Monster Energy a signature beverage "Gronk" that will be distributed by Coca-Cola.

In 2015, Klarberg gave the commencement address at alma mater Pace University to the undergraduate Class of 2015 and received an honorary doctorate degree.

He currently manages recording artist Nicki Minaj, artist Alec Monopoly, entrepreneur Russell Simmons,[7] DJ and record producer Kaskade, several top NASCAR drivers, DJ and record producer John Summit, Anna Kournikova, MLB All-Star C. J. Wilson, MLB All-Star and Homerun Champion José Bautista, professional soccer player Jozy Altidore, and NHL Hall-of-Famer Mark Messier,[8] amongst others.

[26] In April 2016, Klarberg represented NFL star Rob Gronkowski and launched with Monster Energy a signature beverage "Gronk" that will be distributed by Coca-Cola.

[27] In 2016, Josh Klein became a partner in Monarch, whose clients include The Chainsmokers, Big Sean, Logic, DJ Snake and Kelly Rowland.

[citation needed] In April 2012, Klarberg, along with Sara Herbert, was honored with the National Meningitis Association Nancy Ford Springer Inspiration Award for his long-standing support of NMA’s fight against the vaccine-preventable disease.

In 2015, Klarberg gave the commencement address at alma mater Pace University to the undergraduate Class of 2015 and received an honorary doctorate degree.

In September 2024, Big Noon Kickoff featured Klarberg's sports management class in a segment starring Mark Ingram II and Urban Meyer.

[39] In Fall 2024, Klarberg lectured at the London School of Economics as a three-part series discussing business development in sports.