Only daughter of Lord Mace Tyrell and Alerie of Hightower, born at Highgarden and raised under the sharp tutelage of her grandmother Olenna, the Queen of Thorns. Her brothers were Willas the heir, lamed in a tourney by Oberyn Martell; Garlan the Gallant, second of the three; and Loras, the Knight of Flowers, who took the white cloak of the Kingsguard. About her in King's Landing went her cousins three, Megga, Alla, and Elinor Tyrell, sworn handmaids and bedmates who shared her every confidence.
She was first wed at Highgarden to Renly Baratheon when the Tyrells declared for his claim against his brothers, a match her grandmother arranged for a crown and not for love, and one her bridegroom never consummated for the love he bore her brother Loras. When Renly was cut down before Storm's End by a shadow with Stannis Baratheon's face, House Tyrell turned its strength against Stannis on the Blackwater, and Lord Tywin Lannister, his army newly arrived, accepted Margaery's betrothal to King Joffrey Baratheon in payment. She came to court styled Maid Margaery and won the smallfolk with bread and alms while she learned from Sansa Stark the truth of the boy she was to wed.
Joffrey choked to death at their wedding feast in the poisoning long after called the Purple Wedding, and the Tyrells, undeterred, wed her at once to his younger brother Tommen, the new king and still a boy of eight. In the city she grew bold against Queen Cersei, until Cersei, having granted the Faith its swords again, set the High Sparrow upon her with the charges of adultery, fornication, and false witness sworn by the singer Hamish the Harper and others. Margaery was seized in the Red Keep with her cousins three and her brother Loras, and confined to a cell of the Great Sept of Baelor to await her trial before the gods.