Shelley Lee Long was born at 7:15 am on Tuesday, August 23, 1949 in Indian Village, Fort Wayne, Indiana, USA, the only child of Ivadine (Williams), a schoolteacher, and Leland Long, a teacher who had previously worked in the rubber industry. Shelley attended school at Kekionga Junior High for grades 6-9 and at South Side High School for grades 10-12. She enrolled at Northwestern University in 1967 as an undergraduate studying drama. Her first job was at the university as a meal plan checker. She left Northwestern to pursue a dual career in acting and modeling. She also had a brief marriage to her first husband that ended in divorce. In Chicago, she became a member of the celebrated Second City troupe, in addition to writing, producing and co-hosting a popular Chicago magazine program called "Sorting It Out" in 1975. The show ran for three years on a local NBC station and won three Emmy Awards for Best Entertainment Show.

She met her second husband, Bruce Tyson (a securities broker), on a blind date in 1979. They were married in October, 1981. In 1982, she played the character Diane Chambers in the new NBC comedy series, Cheers (1982). She played the part for five years, winning an Emmy for Outstanding Lead Actress in a Comedy Series in 1983, winning Golden Globe Awards for Best Supporting Actress in a Comedy Series in 1983, for Best Actress in a Comedy Series in 1985 and a Quality TV Award for Best Supporting Actress in a Comedy Series in 1986. She gave birth to a daughter, Juliana, on March 27, 1985. On her summer hiatus from "Cheers", Long made feature films, receiving a Golden Globe nomination as Best Actress for Irreconcilable Differences (1984). In 1987, she starred in the hit comedy Outrageous Fortune (1987) with Bette Midler. Soon after, she left "Cheers" after five years to embark on a film career. However, her films Hello Again (1987) and Troop Beverly Hills (1989) were not hits, and she returned to television appearing in the final episode of Cheers in 1993. That same year, she appeared in her own television series "Good Advice" (1993) which was canceled. She returned to feature films playing Carol Brady in the The Brady Bunch Movie (1995). The film became a hit and spawned a sequel, A Very Brady Sequel (1996), which wasn't a hit. She returned to television playing the title role in "Kelly Kelly" (1998), which was canceled after a few episodes. She also played Diane Chambers a few times on "Frasier", the spinoff of Cheers. Her personal life took a huge blow when her husband divorced her in 2004 after more than 20 years of marriage. She recovered and continued on with her career, appearing in guest-starring roles on television, including a recurring role on Modern Family (2009). She supported her daughter Juliana Long Tyson's decision to follow in her footsteps as an actress. She also encouraged Juliana to get married, which she did in 2015, to management consultant Ryan Kissick. Shelley herself never remarried after her two divorces but continues to work in television.