The Messenger of Allah ﷺ married her when she was six years old and consummated the marriage when she was nine.
أخبرنا إسحق بن إبراهيم قال أنبأنا أبو معاوية قال حدثنا هشام بن عروة عن أبيه
أن رسول الله ﷺ تزوجها وهي بنت ست وبنى بها وهي بنت تسع
Bukhari narrated it in "Virtues of the Ansar," chapter "The Prophet's ﷺ marriage to Ayesha, her arrival in Madinah, and his consummation of the marriage with her," hadith no. 3894, and elsewhere, and Muslim narrated it in "Marriage," chapter "The permissibility of a father marrying off his young virgin daughter," hadith no. 70/1422, from the hadith of Hisham through this same chain. It is also found in Kubra, hadith no. 5366. Abdul-Rahman bin Abu Zinad Madani narrated it from Hisham through this same chain (Ahmad, 6/118).