Blair Patricia Warner is the daughter of David and Monica Warner. She has has a cousin named Geri Tyler. Wealthy and rebellious in her youth, she was oft times seen smoking cigarettes, drinking beer and enjoying great popularity with boys; unlike many of her classmates. She was very social and enjoying dating good-looking boys. She considered shopping her favorite hobby, often getting new clothes from Bloomingdale's and Neiman Marcus. In her youth, she dabbled a bit in ventriloquism, only confessing to it several years later.
Blair was sometimes very vain and believed that she was perfect in every way but she was also funny, kind-hearted, and loving to Mrs. Garrett and her friends, even to Jo Polniaczek, who was initially her rival. She also got good grades, won school awards, was crowned Harvest Queen for three straight years and even once convinced a guy to move from Switzerland to attend school near her. She often felt she was more important than "regular" people because she was the heiress to her father's multi-million dollar Warner Textile Mills. Any crisis at Eastland often prompted a suggested solution from Blair, preceded by her catch phrase ("I just had another one of my brilliant ideas!") More often than not, though, her "brilliant ideas" had quite opposite results and likely just an effort to feed her ego. On at least two occasions, her idea turned out to actually be good. It was Blair's idea for Mrs. Garrett to punish the girls after Tootie was caught drunk on wine that Blair was responsible for as if they went to the headmaster, they would have all been expelled since Natalie and Jo were involved as well. It was also her idea to return to kitchen duty after getting into a paint fight, resulting in expensive repairs to their old room.
She eventually developed a more down-to-earth attitude, especially after she suffered a car accident from falling asleep at the wheel. It left her slightly scarred, spoiling her "perfect" beauty. Blair's parents divorced on June 14, 1973, and although she didn't usually show it, Blair wished that she had more of a happy family like all of her friends. Eventually, her mother remarried for the fourth time and gave birth to a baby girl named Bailey. Initially, Blair had misgivings about her mother's pregnancy but fell in love with Bailey as soon as she saw her. Another secret Blair kept from her friends was that her Cousin Geri had Cerebral palsy. It was soom revealed she was not embarrassed by her cousin but rather jealous of her, since Blair was used to being the center of attention. Mrs. Garrett told Blair not to lash out against Geri because of her jealousy, and Blair eventually joined Geri, a successful comedian, onstage at an impromptu comedy show G at the Eastland Academy.
Blair also has a sister, Megan Warner, who visited Eastland to reveal to her her choice to become a nun. It forced Blair to confess she considered herself an atheist because God didn't prevent her parent's divorce in 1973. When her parents split up nevertheless, she chose to believe that God didn't exist because if He had, her parents would have stayed together.
Blair attended Eastland Academy for Girls, While attending there, she became close friends with Nancy Olson, Sue Ann Weaver, Molly Parker, Tootie Ramsey, Natalie Green and eventually Jo Polniaczek, who was her chief foil. The two made no secret of their mutual dislike to each other. Jo found Blair spoiled and snobbish, and Blair thought Jo was classless and crude. However, more than a few times Blair stuck up for and stood by Jo in her time of need (and vice versa) and eventually the two developed a much friendlier relationship. Jo even once declares Blair as her official best friend. When Blair learned that her maternal grandfather, Judge Carlton Blair, was a racist before having his name immortalized on the school library, Jo talked her out of pulling the funds out of the library and instead giving up on some of her ego to name it something else.
Over the next several Years, Blair, Jo, Natalie and Tootie became close and treated each other other like sisters. Upon graduating Eastland in 1983, she and Jo attended Langley College, losing contact with Natalie and Tootie briefly. Originally living in the dormitory on campus, she soon chose to live in an apartment over Edna's Edibles to be closer to Mrs. Garrett and her friends. After the eatery burned down, Blair and her friends joined together to create the shop, Over Our Heads on the site. After graduating from Langley, she enrolled in law school, but upon discovering that Eastland had become financially troubled, she paid for the property and converted it into a co-educational school.
Several years later, Blair became a hotel mogul to a successful hotel empire under the umbrella of Warner Enterprises with her husband, Tad Warner. In her absence, Eastland had closed down completely, and Jo, Tootie and Natalie came together for one last reunion. During these events, she began to suspect that Tad may have been having an affair when a woman answers his phone, but she soon learns that he's actually been volunteering at a children's shelter. The realization made her realize that she wanted to start a family.
- Through the series, Blair's delusions of grandeur were usually played for laughs when Natalie, Tootie or Jo would make sarcastic remarks about her "beauty", "perfect" personality, or "naturally blonde hair."
- In addition to the Diff'rent Strokes episode "The Girls School" that serves as the pilot for The Facts of Life, Blair appears in "The Older Man".
- Actress Geri Reischl ("Fake Jan" of The Brady Bunch Hour) was initially given the role of Blair Warner in the television pilot Garrett's Girls, which later became The Facts of Life), but was forced to give it up due to her contract with General Mills.