Wasserman obtained a Bachelor of Arts degree in Political Science from the University of California at Los Angeles (UCLA). He credits his grandfather, Lew Wasserman, head of MCA, as his greatest teacher. The two would have breakfast together every Saturday and Sunday from the time when Casey was a child to the elder Wasserman's death in 2002. The younger Wasserman said, "He was my most valuable resource in terms of information. In broad terms he knew what he wanted to do and I followed in his footsteps." After graduation from UCLA, Casey Wasserman worked as an investment banker.
In 1998, he purchased the Los Angeles Avengers of the Arena Football League (AFL). He paid about $5 million for the franchise rights. Despite his youth, he was elected chairman of the league. In 2002 he negotiated a groundbreaking national television partnership between the league and NBC television, as well as the collective bargaining agreement with its players. On Saturday, April 18, 2009, Wasserman sent an email to AFL's de facto commissioner informing him of his decision to terminate the L.A. Avengers' membership in the Arena Football League.
The same year that he purchased the football team, Casey Wasserman started Wasserman (then-called Wasserman Media Group), a sports marketing and talent management company, of which he remains CEO.
In 2002, WMG acquired the sports marketing and naming-rights company Envision and the action sports marketing and representation firm The Familie, based in Carlsbad, CA.
In 2004, WMG purchased 411 Productions and a few months later relaunched it as Studio 411, a sports entertainment film studio. The business was designed to provide financing, obtain sponsorships and arrange distribution in support of original productions. The company also made an unsuccessful bid to sign up enough athletes in BMX, skateboarding and freestyle motocross to form PGA-like sanctioning bodies in those sports.
In January, 2006 WMG acquired the NBA and MLB sports agent business of Arn Tellem, a well-known sports agent who joined WMG as well. Several of Tellem's sports agent colleagues also joined the company as part of the deal. Until he retired in June, 2015, Tellem was a principal at the company and ran one of its management groups.
In November 2006, the company acquired soccer agency, SFX, in the UK. Through that acquisition, WMG came to represent such players as Steven Gerrard, Robbie Keane, Jamie Carragher, Michael Owen, Tim Cahill, Jonathan Woodgate, Wes Brown, Scott Parker, Jack Wilshere, Park Ji-Sung, Shay Given, Tim Howard and Emile Heskey.
In June 2007, WMG expanded its consulting and media and property capabilities by purchasing Raleigh, NC-based OnSport.
In early 2011, WMG bought London-based media rights manager and advisory firm Reel Enterprises.
That year WMG expanded its golf talent roster by acquiring SFX Golf in April 2011.
Wasserman acts as President and Chief Executive Officer of the Wasserman Foundation, a charitable organization founded by Lew Wasserman and his wife Edie in 1952. He sits on two of the Motion Picture and Television Fund's three boards of directors - the MPTF Corporate Board and the MPTF Foundation Board. In an April 13, 2009, article in the Los Angeles Times, Wasserman is quoted as having explained that the decision of the MPTF Boards to close its hospital and transfer its elderly long-term care residents would "allow [the MPTF] to thrive for generations." In an August 29, 2015, article in the Los Angeles Times, Wasserman, advocating the city of Los Angeles to bid for the 2024 Summer Olympics without specific provisions to protect the city from cost overruns, is quoted saying "The city and the council and the communities need to be engaged and supportive. Otherwise, we won't be successful regardless."
Wasserman co-chaired a fundraiser for Hillary Clinton's presidential campaign on August 22, 2016.