He is the founder and CEO of Top Rank, a professional boxing promotion company based in Las Vegas.

[6] In 1963, as a prosecutor for the Department of justice, Arum's work led to the indictment of the president of the Washington Heights Savings and Loan Association, Floyd Cramer, for leading a mortgage tax-evasion scheme.

Cramer committed suicide hours after being indicted, at which time Arum recalled, "What kind of person causes another man to take his own life?

[14] In 1994, he tried to add basketball to his interests, joining forces with Fred Hofheinz and Louisiana politicians to purchase and relocate the Minnesota Timberwolves to New Orleans, but the deal was rejected.

[17] In 2016, he put together an all-Hispanic undercard for Manny Pacquiao vs. Timothy Bradley III in protest of then-presidential candidate Donald Trump's statements on Mexican immigration.

[19] As a boxing promoter, Arum had been involved in many spats and controversies, including a 40-year feud with Don King,[20][21] with whom he has co-promoted several fights.

The fights were called off at the last minute when Barry Hearn scuttled the bout by withdrawing his fighters, when no purses were forthcoming from Top Rank.

[27] In 2000, citing extortion, Arum voluntarily testified to having paid IBF president Robert W. "Bobby" Lee Sr. $100,000 in two installments in 1995, as the first half of a $200,000 bribe, through "middleman, Stanley Hoffman", adding that Lee had first demanded $500,000 to approve the Schulz–Foreman fight but had settled for the lesser amount of $200,000 (half of which was never paid).

[29] Boxing promoters Cedric Kushner and Dino Duva also admitted to making similar payments to Lee.

[29] Oscar De La Hoya successfully sued Arum and was legally released from his contract with Top Rank in January 2001.

[33] In the first week of January 2004, FBI agents raided Arum's Top Rank office in Las Vegas.

In 2007, Yahoo Sports reported that, "Floyd Mayweather Jr. essentially accused Arum, who promoted him from the beginning of his career in 1996 until 2006, of underpaying him, exploiting his talents and manipulating officials.

"[20] Mayweather, who also became a boxing promoter, stated to Yahoo Sports in 2015, "I don't have anything bad to say about Bob Arum.

Arum complained that HBO dropped Mayweather from his exclusive deal after he insisted his fighter have a tougher bout than the network wanted.

[43] Arum was a close friend and business partner of the late billionaire casino tycoon, and CEO of Las Vegas Sands Corp, Sheldon Adelson.

[46] Arum, who appeared as corrupt DEA agent "Stokes" in the 1975 film The Marijuana Affair at the behest of his friend, Jamaican-born boxing promoter, filmmaker, bookie, and horse-racing aficionado Lucien Chen (June 6, 1928 – December 16, 2015), has advocated for the decriminalization of cannabis; and, in a 2017 interview, stated that he had started smoking it in 1966, declaring, "Cannabis is good for you!

It's these damn people during the Nixon administration that really put cannabis into the position where it was a drug like heroin and cocaine and that was wrong" and adding that "in a lot of ways, marijuana is better for the athlete as pain medication than the drugs.”[47] In a 2017 VICE interview (which erroneously reports film producer Chen as Shen); Arum was also quoted as saying, "I think the NFL is gonna revise its policy on marijuana and I think everybody should.