In April 1986 Reynolds, a Republican, went with a friend to a meeting with Senator Robert Packwood, where the issue of a proposed cut in tobacco tax was raised. Outraged, Reynolds stood up and asked why tobacco taxes were so low. By June 1986, Reynolds had become an anti-smoking activist, appearing in adverts for the American Lung Association and testifying before a congressional subcommittee at the invitation of Packwood, to the dismay of his family. He had already sold his tobacco stock in 1979, and tried to get hired by RJR Nabisco Inc. from 1983-85, in an attempt to get the company to divest their tobacco holding. Reynolds was himself a smoker for 10 years until he quit in 1985 after five years of trying. He has appeared on many national television programs.

In 1989, Reynolds founded The Foundation for a Smokefree America. That same year, Reynolds published The Gilded Leaf with Thomas Schactman, chronicling three generations of his family and its tobacco business, a book he had been working on since 1980. The book was re-issued in 2006 (ISBN 0-595-83831-6).

Former Surgeon General, C. Everett Koop M.D., called him "one of the nation's most influential advocates of a smokefree America." He continues to speak regarding tobacco control to groups, with a focus on high school and elementary school audiences. In 2009, he advised the Greek government on anti-smoking measures.

His mother was his father's second wife, an actress who starred as Marianne O'Brien in the 1940s, contracted to Jack Warner. His parents separated when he was three and he did not meet his father again until he was nine. His father died five years later from emphysema aged 58, leaving a will that disinherited Patrick and his brother and four half-brothers. He received $500,000 from his father's fourth wife in agreement not to contest the will. He inherited $2.5 million from his grandfather in 1969, when he was 21. He studied drama at the University of California, and dated actress Shelly Duvall. He recorded three unsuccessful pop singles in 1982. He married his first wife Regina in Ofterschwang, West Germany in July 1983, and briefly began working for her father's international bus company before landing his role in Eliminators. His mother died in 1985.

He lives in Los Angeles with his wife Alexandra and their son, born in October 2009.