Fleming was born in San Jose, California, the daughter of Doris Elizabeth (née Deal) and Albert Eugene Fleming, a newspaper journalist. She began skating at age nine when her family moved to Cleveland and soon began skating in earnest on the advice of her father. In 1961, when Peggy was twelve years old, her coach William Kipp was killed in the crash of Sabena Flight 548 along with the rest of the United States figure skating team while en route to the 1961 World Figure Skating Championships. Fleming was subsequently coached by Carlo Fassi. Her unusual style led to five U.S. titles, three World titles and the gold medal in the 1968 Olympics in Grenoble, France. Her award in Grenoble was singularly important for the American athletes and the nation as a whole, for this was the only gold medal that the U.S. Olympic team won in the 1968 Winter Games. It signaled a return to American dominance in the sport of women's figure skating following the unprecedented tragedy of the 1961 plane crash.
Peggy Fleming was diagnosed with breast cancer in 1998. The cancer was detected in its early stages, and surgery was successful. She became a breast cancer activist who recommends not procrastinating and advocates for early detection.
In June 13, 1970, Fleming married her teenage sweetheart Greg Jenkins, a dermatologist and a former amateur pair figure skater. The couple have two sons, Andy in 1977, Todd in 1988, and three grandchildren. They also owned and operated Fleming Jenkins Vineyards & Winery in California. The winery produced close to 2,000 cases of wine a year with such brands as "Choreography Cabernet" and "San Francisco Bay Syrah Rosé." Profits from the "Victories Rosé" went towards charities that supported research towards breast cancer. The winery closed in 2011.
In 1988, a Peggy Fleming all-porcelain doll was made by Franklin Mint Heirloom Porcelain Dolls.
Along with former Olympian Vonetta Flowers, Fleming was injured and briefly hospitalized after a traffic accident while riding in US Vice President Joe Biden's motorcade at the Winter Olympics in Vancouver in February 2010.
In 2011, Fleming became spokesperson for the Robitussin® "Last Names Giveaway", since her last name sounds like one of the cold and flu symptoms Robitussin® treats (phlegm), per the rules of the contest.
Peggy Fleming is mentioned very prominently in the Peanuts comic strip during the late 1960s and early 1970s, with Snoopy clearly having a crush on her.
On February 22, 2011, the Trey Anastasio Band performed a song about Fleming, titled "Peggy".
In an episode of Community, Ben Chang dresses as Peggy Fleming for the school Halloween dance and accuses anyone who mistakes him for an Asian skater of being racist. Shirley correctly identifies him, saying that "[she's] always loved Peggy Fleming."