Ngô Văn Sở was a general of Tây Sơn dynasty. Born in Tuy Viễn District, Bình Định Province. He joined the Tây Sơn army in early time. In 1787, Vũ Văn Nhậm led an army marched north into Tonkin. Ngô Văn Sở and Phan Văn Lân followed the army to assist him. Nhậm occupied Thăng Long, had Nguyễn Hữu Chỉnh executed, installed Lê Duy Cận as a puppet "Prince Regent". Sở and Lân reported Nhậm's actions to Nguyễn Huệ. Huệ led an army marched north and had Nhậm executed. Huệ retreated from Tonkin, and left Ngô Văn Sở, Phan Văn Lân, Nguyễn Văn Tuyết, Nguyễn Văn Dụng, Trần Thuận Ngôn and Ngô Thì Nhậm in Thăng Long to watch Cận. Qing China invaded Vietnam to reinstall the deposed emperor Lê Chiêu Thống of Lê dynasty. Sở ordered Cận to write a letter to the Qing viceroy Sun Shiyi. Cận described himself as a popular ruler and tried to persuade Sun to retreat. But it was rejected by Sun. Realizing Tây Sơn army could not stop Chinese army from marching to Thăng Long, Sở accepted the suggestion of Ngô Thì Nhậm, abandoned Thăng Long, and retreated to Tam Điệp, and sent Nguyễn Văn Tuyết to Phú Xuân to ask support. Huệ then led an army march north, and defeated Chinese army in Ngọc Hồi and Đống Đa. Sở also played an important role in this battle. After the war, Huệ attempted to find a peaceful solution with Qing China. Sở was sent to China as a member of diplomatic corps. Finally, Nguyễn Huệ was recognized as the new ruler of Vietnam by Qianlong Emperor. The young emperor Nguyễn Quang Toản ascended the throne in 1792. In the next year, Quy Nhơn was attacked by Nguyễn lord. Nguyễn Nhạc was defeated, and asked for Toản's help. Sở led troops to reinforce Quy Nhơn together with Phạm Công Hưng, Nguyễn Văn Huấn and Lê Trung. Nguyễn army had to retreat. Sở was a political ally of Bùi Đắc Tuyên. In 1795, Sở was sent to Tonkin to replace Vũ Văn Dũng. Dũng was ordered to came back to Phú Xuân. On the way to Phú Xuân, Dũng was persuaded by Trần Văn Kỷ to stage a coup against Tuyên. Tuyên was arrested and thrown into prison. Sở was arrested by Nguyễn Quang Thùy and taken to Phú Xuân. He was thrown into Perfume River together with Bùi Đắc Tuyên and Bùi Đắc Trụ.
