He was the eldest son of Lý Thái Tông and his consort was known as Empress Mai Thị. He was born on February 25, 1023 at Càn Đức palace. In 1028, he was conferred Crown prince after his father ascended the throne. He was soon adept in all main fields at that time, such as history, literature, music, and also martial arts. Like his father, he was soon brought out of the capital citadel to touch the bottom class in society, following the tradition of this dynasty. Living among the masses, he soon profoundly understood the real conditions of the society, making him have a benevolent reign after his succession. Just at the age of 15, he was dubbed as General Marshal, suppressed the revolt in Lam Tây, and made some feat. When was 17 years old, his father allowed Thanh Tong to lead an army to conquest Nùng Tồn Phúc, he was in charge of the Regent to rule over the capital and to manage the affairs of court. In 1040, when he was just 18, all important litigations over the nation were committed to him. One edifice known as Quảng Vũ palace was confided to him. In 1043, he was again conferred as General Marshal, taking charge of the suppression of rebellions in Châu Ái. One year later, his father personally led troops in the invasion of Champa. While Thái Tông was absent, the crown prince acted as Regent Protector of the Imperial Capital. Late 1044, the emperor returned victoriously from Champa. In January 1045, when he was ailing, Lý Thái Tông allowed him to hold court. Two months later, Lý Thái Tông died and then Lý Nhật Tôn officially ascended.
Emperor
Just after succession, Lý Thánh Tông changed the national name from "Đại Cồ Việt" to "Đại Việt", initiating the most prosperous epoch throughout the history of Vietnam under that name. Lý Thánh Tông ably managed the nation through his reign and was regarded as a relatively benevolent emperor. According to the official histories, in one year, when it underwent an extraordinarily cold and long winter, he told his confidants that even he, being in the palace with enough clothing, still felt cold, so that prisoners are likely to be not sufficiently supplied with either food or clothing, and easily deceased. Thus, he commanded his servants to bring food, mats, and blankets to these prisoners. On another day, he was adjudicating some important cases. One of his young princesses was standing near him; he then indicated her and said that his love toward common people equaled that toward his offspring. He also said that the code was not stretched through the people so that they were ignorant and also could be innocent because of this ignorance. Thus the rigidity of the code must have been decreased and the laws must have been aimed at humanity. Under his capable reign, the country was relatively stable and peaceful. Despite that, there were still some rebellions that the emperor suppressed at ease. He practiced Buddhism so during his reign, Lý Thánh Tông built many tower-pagodas and cast some large and impressive bells. However, he also had a comparative respect to Confucianism, and in order to civilize the people, he operated "Văn Miếu", the Temple of Literature, and commanded workmen to carve some large sculptures of Confucius and 72 sages. Since that, Vietnam has had Văn Miếu, the site to commemorate all people who have achieved the title "Tiến sĩ". His success was contributed to notably by his Noble Consort Ỷ Lan, who displayed great competence in administration. As Lý Thánh Tông did not soon produce an heir, when he went to war, she herself was left in charge of administering the nation.
After stabilizing the nation, he attended to the extension of his realm. He rearrayed the army and made army titles for each part of it. He totally divided his main cohort into 100 small groups and those were arrayed into four large groups: left, right, front, and rear, with supports of cavalries and trebuchets. The allotted army was assembled in another part. The tactical factor of the Đại Việt army at that time was an advance which was respected by its rivals. In 1060, he commanded the exarch of "Lạng Châu" to combat the Song army along the border between two nations. The Vietnamese infantry won and captured the Song general. After some more failed conflict with Đại Việt, the Song sent an envoy to negotiate with the Đại Việt court. The negotiator was treated well, but Đại Việt peremptorily did not free that general. As Champa constantly harassed the area near the border between the two nations and sometimes intruded deeply to loot, in 1069 Lý Thánh Tông himself led an army to defeat Champa. He defeated the Cham army, burned Vijaya, and captured the King of Champa, Rudravarman III. Rudravarman III implored Lý Thánh Tông to release him in exchange for three areas, known as Địa Lý, Ma Linh, and Bố Chính. These now form part of Quảng Bình Province and Quảng Trị Province).
Era name
In January 1072, he suddenly died at the age of 50, having ruled for 17 years. During his rule, he used 5 era names:
