Murdock was born on April 11, 1923, in Kansas City, Missouri. His Father was a traveling salesman, while his mother took up laundry and scrubbed floors to make ends meet. He is the middle child of three; he had two sisters. He was particularly close to his mother, who died at 42 from cancer. He grew up in Montgomery Township, Ohio, and dropped out of high school in the 9th grade. He was drafted by the United States Army in 1943 during World War II.

When the real estate market collapsed in the 1960s, he moved to Los Angeles where he continued developing real estate opportunities, leading to a string of acquisitions. In 1978 he acquired control of International Mining. In early 1980s he became the largest shareholder in L.A. based Occidental Petroleum, by selling the corporation his 18% share of the Iowa Beef Packers company.

Murdock owned Cannon Mills in Kannapolis, North Carolina, from 1982, after the death of Charles Cannon, until 1985, when he sold the company to Fieldcrest.

He has helped contribute to the redevelopment of a 5,800,000-square-foot (540,000 m) complex in Kannapolis, North Carolina, of a biotechnology research center, the North Carolina Research Campus. The research center is a joint public-private venture, involving major North Carolina universities and private investment. The site of the research center in the middle of Kannapolis was formerly occupied by Plant #1 of Cannon Mills (which became Pillowtex after a series of mergers and acquisitions). Pillowtex filed for bankruptcy in 2003, and closed the mill. This resulted in the largest mass layoff of workers in North Carolina history. Murdock acquired the site and demolished the mill in 2006.

Since the death of his third wife, Gabriele, he has been involved to finding a cure for cancer, advancing nutrition, and life extension. He established the Dole Nutrition Institute to advocate the benefits of a plant-based diet to promote health and prevent disease. With the help of UCLA, he oversaw the writing of the Encyclopedia of Foods, A Guide to Healthy Nutrition. In 2006, he opened the California Health and Longevity Institute (CHLI).

He has been married five times. In 1967, he married his third wife, Gabriele; they had two children together and he also adopted her son from a previous marriage, Eugene. Gabriele was diagnosed with ovarian cancer in 1983 and died in 1985. A year later, Eugene died after hitting his head while swimming in the family estate's swimming pool. In 2004 his son David Jr. died in an auto accident on the Santa Monica Freeway. His remaining son Justin serves as CEO and executive chairman of NovaRx and is senior vice President of Investments for Castle & Cooke. Previously, he was a Director at the Dole Food Company, as well as their audit and Finance committee until his retirement on May 17, 2013. In 2011, Forbes ranked David Sr. as the 190th-richest person in the "Forbes 400" list and 613th in the "World's Billionaires" list, with a net worth of US$2.4 billion as of March 2013.