Spears was born and raised in McComb, Mississippi to Barney O'Field Bridges, an American G.I. (1919—1978), and Lilian Irene Portell (1924—1993), who was a native of Hendon, London, where she married in 1945. Her maternal great-grandfather, Edward Portelli, was Maltese and emigrated to England, where he married Alice Taylor. Spears has an older brother, Barry "Sonny" Bridges (born 1951), and had an older sister, Sandra Bridges Covington (born 1947), who died of ovarian cancer in 2007.

In 1975, she married James "Jamie" Spears (born 1952). The Spears have three children: son Bryan James (born 1977) and daughters Britney Jean (born 1981) and Jamie Lynn Marie (born 1991). Britney's 2004 marriage to Kevin Federline produced two grandsons: Sean Preston Federline (born 2005) and Jayden James Federline (born 2006), and one granddaughter resulted from Jamie Lynn and her boyfriend Casey Aldridge: Maddie Briann Aldridge (born 2008).

Lynne opened and worked in her own day care in their hometown of Kentwood, Louisiana. The 11-year-old Britney eventually joined the new Mickey Mouse Club for the 1993-94 season. Following this, Lynne earned her bachelor's degree and became an elementary school teacher in Kentwood, until she was asked by management to accompany Britney on the Dream Within a Dream Tour in 2001.

In 2008, her representative reported to the National Enquirer that in 1975, she was driving her injured brother to the hospital in Kentwood when she accidentally hit and killed the 12-year-old Anthony Winters, who was riding his bicycle. The representative subsequently released a statement: "Anthony Winters and his friend were in the road on a curve on a bicycle. As Lynne rounded the curve she could not avoid the boy in the street as there was oncoming traffic in the opposite lane... Lynne realized the boy was struck immediately and to this day is grieved by the Winters’ loss of their son."

Lynne has co-written two books with her daughter Britney. The first, Heart to Heart, was published in 2000 as a biographical book about Britney. A Mother's Gift was a novel released in 2001 and has been adapted into a TV movie, Brave New Girl. A 2008 memoir, Through The Storm: A Real Story of Fame and Family in a Tabloid World, became a New York Times Bestseller. She has a strong Christian faith, and openly discusses this in her memoir.Biographers cite Lynne as the main driving force and support behind Britney's early career, but in her memoir, she explains she was not the "pushy stage mom" she has been described as, but merely a supporter of her daughter's quest to achieve her dreams.