Born in 1923 to infamous San Francisco private investigator William V. Peekaboo Pennington, Bill Pennington served as a bomber pilot in World War II, before settling in Nevada. He was working as a slot machine executive when he and William Bennett pooled their life savings of 40,000 to revitalize the Circus Circus Hotel and Casino in Las Vegas in 1974. The casino was the first to seek the family trade and target tourists who wanted a taste of gambling, an affordable room, and entertainment for the family. In the years that followed, they expanded the Las Vegas property and opened Circus Circus Hotel and Casino in Reno in 1978. The partners took the company public on October 25, 1983, at 15 per share. By the end of the day, Circus Circus Enterprises, Inc. was trading at 16.87. Revenue generated from investors added to the resort revenue providing the resources for additional growth and expansion, including acquisition of other properties.

After a serious boating accident at Lake Tahoe in the mid 1980s, Pennington scaled back his personal involvement with the business. He retired in 1988 and sold the remaining stake in the company in the mid-1990s. The astounding success of Circus Circus was the result of Penningtons and Bennetts ability to focus on a family-oriented market not previously attracted to Las Vegas, while implementing a system of high accountability for resort management.

Pennington is a long-time supporter of University of Nevada, Reno. He and his wife, Susan, also support a number of charitable organizations. He has two grown children.