During his career as a defense attorney, Goodman represented defendants accused of being some of the leading organized crime figures in Las Vegas, such as: Meyer Lansky, Nicky Scarfo, Herbert "Fat Herbie" Blitzstein, Phil Leonetti, former Stardust Casino boss Frank "Lefty" Rosenthal, and Jamiel "Jimmy" Chagra, a 1970s drug trafficker who was acquitted of ordering the murder of Federal Judge John H. Wood, Jr. One of his notorious clients was Chicago mobster Anthony "Tony the Ant" Spilotro, who was known to have a short and violent temper.

In the semi-factual 1995 movie Casino, the character of Nicky Santoro was based on Spilotro, and was portrayed by actor Joe Pesci.

Goodman had a cameo appearance in the film as himself, where he was depicted defending “Ace Rothstein,” a character closely based on Lefty Rosenthal, and played by Robert De Niro.

[4] Goodman also represented former San Diego Mayor Roger Hedgecock, who was convicted of accepting illegal campaign contributions, and eventually forced to resign.

[citation needed] Goodman worked to get a National Football League team to relocate to Las Vegas.

In 2017, under the tenure of Carolyn Goodman as mayor, the Oakland Raiders agreed to relocate to Las Vegas.

Goodman supports legalizing prostitution in the city's downtown area as a revenue generator and tool for revitalization.

[20] His memoir, Being Oscar: From Mob Lawyer to Mayor of Las Vegas,[21] written with George Anastasia, was published in 2013.

Goodman fueled speculation that he might run as an independent in the 2010 Nevada gubernatorial election against incumbent Republican Jim Gibbons and presumptive Democratic candidate Rory Reid.

[23] However, Goodman decided not to run for governor, citing his desire to stay close to his family, and objections to moving to Carson City.

[24] Las Vegas commentator Dayvid Figler wrote in 2009 that Goodman might become the first Jewish president of the United States.

[25] Goodman appeared as himself in the 1995 Martin Scorsese film Casino, reprising his real life role as a lawyer for both Frank Rosenthal and Anthony Spilotro, respectively renamed Sam Rothstein (Robert De Niro) and Nicky Santoro (Joe Pesci).

As a celebrity photographer for the Playboy Cyber Club, Goodman shot a topless pictorial of Miss January 2001 Irina Voronina for the website.

The episodes Goodman was featured in included: “Early Rollout,” as a lawyer for a suspect during an interrogation; “Sqweegel,” where he defended Ann-Margret's character from being harassed by the LVPD; and “Maid Man,” where he was shot while emceeing the opening of the Mob Museum, which was re-created for the show in advance of its opening.