Lorelai "Rory" Leigh Gilmore is the only child of Lorelai Gilmore and the first-born daughter of Christopher Hayden, born on October 8, 1984 at 4:03 a.m. Rory shares her mother's taste in junk food, coffee, movies, music, and much more. They both exhibit a talent for witty, fast-paced, pop-culture-laden dialogue, and they are extremely close. Rory spent her childhood in the Independence Inn in Stars Hollow where her mother originally worked as maid. Lorelai was later able to buy a house, where Rory spent her adolescent years. Rory did not have much contact with her grandparents,Richard and Emily, until she started to attend Chilton. She quickly grew close to her grandparents, especially her grandfather. This was often a source of contention between Rory and Lorelai, who had a tumultuous relationship with her parents.

Rory attended the prestigious Chilton Academy for her sophomore, junior and senior years of high school. To pay tuition, Lorelai had to ask her estranged parents for help. They agreed to pay on one condition: Lorelai and Rory would have to come to their house every Friday night for dinner. This tradition continued after graduation as Richard and Emily agreed to pay for Rory's college tuition (and even continued after her financial obligation to them had ended). Rory had no contact with her paternal grandparents, except in the first season when Emily and Richard invite them and Rory's father to a Friday night dinner. After Straub refers to Lorelai as "that girl", stating that Lorelai's pregnancy ruined Christopher's future while making cruel comments about Lorelai, Richard becomes extremely angry, expressing how much he cares for Lorelai and kicks both Straub and Francine out of the house. It was during this time that Emily tells Rory that she had no regrets about her birth, and both she and Richard felt that way but they never want to tell her that.

Before leaving Stars Hollow High School, Rory met fellow school mate Dean Forester, who became her first steady boyfriend. Rory and Dean dated for two and a half seasons before Dean broke it off due to her obvious attraction to 'bad boy' Jess Mariano, the nephew of Luke Danes. Rory and Jess dated, but Jess was often moody, undependable, and secretive, which caused problems in their relationship. Rory later expressed regret about the relationship to her best friend Lane Kim; saying that, while she was initially attracted to Jess' intellectualism and his "bad boy nature," she had become used to Dean's reliability and affectionate nature. She expected Jess to treat her the same way, but she realizes he never would. Jess later decided to leave for California to see his dad without telling Rory, who was graduating from high school at the time. He returned during her freshman year of college and professed his love for her. Though his feelings were reciprocated, Rory would not run away to New York with him.

After graduating from Chilton as valedictorian, Rory went on to attend Yale University, although it had been her childhood dream to go to Harvard. Rory majored in English, although her true interest was journalism; her role model for many years was Christiane Amanpour. After a brief but substantial rekindling of her relationship with Dean Forester, she lost her virginity to him. This was the subject of the first major fight between Rory and Lorelai, as Dean had married another woman after Rory left him, and was still married at the time of Rory and Dean's liaison. Dean eventually ended the relationship during Rory's sophomore year at Yale, when he realized that Rory had entered a world where he could not follow her. After this Rory started to date the heir to the Huntzberger Publishing Company, Logan Huntzberger. Although their relationship began casually as a "no strings attached" affair, Rory's feelings for Logan deepened, and she told him that she would rather be friends than try to be something she is not. He interpreted this as an ultimatum and agreed to exclusively date her. Logan eventually brought Rory to a family dinner at his house, where he introduced her as his girlfriend. Logan's mother and grandfather did not think Rory could handle being married to a Huntzberger and insulted her at the dinner table. Logan's father, Mitchum Huntzberger, gave Rory an internship at one of his newspapers because he felt guilty about his family's awful behavior, but at the end of the internship, he told her that she "just didn't have it" to make it as a journalist. This upset Rory so much that she stole a yacht with Logan as a "joyride". After being caught, she was sentenced to 300 hours of community service. As a result, Rory also rethought her lifelong ambition to become a journalist and decided to take "time off" from Yale. She moved into her grandparents' pool house and accepted a job with the Daughters of the American Revolution. Rory's decision to leave Yale, combined with her decision to move in with her grandparents, caused a massive season-long rift between her and her mother, which was only repaired once Rory returned to school.

Rory returned to Yale after a visit from Jess, who made her realize that her current life (working for the DAR, living under her grandparents' strict rule, not going to school) did not reflect who she truly was. Jess's visit also coincided with a fight between Logan and his father, leaving Logan in a bad mood; after interrupting Jess and Rory's reunion, he proceeded to be arrogant and cruel to Jess, constantly taunting him about his bookstore. This led to a prolonged split-up between Rory and Logan, though they later reunited. However, during the break up, Logan had brief but sexual flings with several other girls. Feeling betrayed, Rory went to Jess's bookstore where she met April, who Luke had taken to meet Jess. After Luke and Jess's friends left, Rory and Jess were alone together. Jess assumed Rory had broken up with Logan and kissed her. Rory reciprocated at first, then pushed him away, explaining that she had just got back together with Logan. Jess was upset by her behavior, telling her that he didn't deserve to be treated in this way. Rory acknowledged that she had behaved badly but confessed she loved Logan in spite of what he had done, that she couldn't seem to stop. Jess said that she could tell Logan that something had happened if that would help, and Rory left. This is the last time Jess is seen in the series.

Around a year later, while her grandparents hosted a graduation party, Logan proposed to Rory, shocking her. After her graduation ceremony, Rory declined because she felt she was too young and had too many opportunities in front of her to tie herself down already. She pleaded with Logan that it didn't have to be "all or nothing" but he said that if she didn't want to marry him, he didn't want to carry on and they broke up for the final time. She later accepts a sudden job offer to work as a journalist to cover Barack Obama's presidential campaign. Luke sets up a surprise farewell party for her. On the day of Rory's departure, Luke opens his diner early, and Lorelai and Rory share a final breakfast before she leaves for her job.