In the late 1930s, Moloney began making gambling equipment, and had great success developing and improving the mechanical slot machines that were the core of the nascent gaming industry.

[3] In the late 1970s, Bally entered the casino ownership business when New Jersey legalized gambling in Atlantic City.

The effort moved forward even though the company was temporarily unable to attain a permanent license for the completed casino.

During this period, company head William T. O'Donnell was forced to resign because of alleged links to organized crime, which he strenuously denied.

The expansion quickly took its toll on the company's finances, and Bally was soon forced to sell off several divisions, including Six Flags in 1987, Bally/Midway, which was acquired by longtime pinball and video game rival Williams Electronics in 1988, and Aladdin's Castle chain of video arcades, in 1989; Aladdin's Castle was later sold to Namco in 1993 and became part of Namco Cybertainment.

[9] The company opened Bally's Saloon & Gambling Hall, a riverboat casino in Mhoon Landing, Mississippi in December 1993.

[12] In 1994, the company changed its name to Bally Entertainment, to reflect its focus on the casino business and the fact that it no longer had any manufacturing operations.

Many casinos and businesses worldwide have used the Bally name and logo in the maze of ownership, division spin-offs and licensing agreements.

WMS Industries has licensed companies to use the intellectual properties and the rights to remanufacture existing Bally and Williams pinball machines.

[21] The company, which changed its name to Light & Wonder in 2022,[22] continues to use Bally Technologies as a subsidiary manufacturing video slot machines and other casino equipment.

[23] Bally Total Fitness, burdened with debt from over-expansion and declining revenues after the 2008 recession, began selling off its clubs in the 2010s.

[34] Former subsidiary Bally Wulff remains a gaming and vending equipment manufacturer in Germany, with additional operations in Spain.