During the decade-long Lam Sơn uprising against the Ming dynasty, Trịnh Khả served as an advisor to Lê Lợi.
Officially, Trịnh Khả was the head of the Administrative Bureau (Chinh-su-vien) but the next four years were filled with intrigue as the various noble families in the court plotted to expand their power at the expense of their rivals.
Trịnh Khả came out on top of this fight, being promoted to the position of Imperial Councilor shortly before Lê Thái Tông became sick and died in 1442.
Real power seems to have been wielded by Trịnh Khả along with Nguyễn Xí, Le Thu and two generals: Dinh Liêt and Pham Boi.
As the years passed, Queen Nguyễn Thị Anh came into greater conflict with the Trịnh Khả and the other oligarchs who ruled the country.
Three hundred years later, the Vietnamese officer, Lê Quý Đôn, said of Trịnh Khả he "served the public good, exhausted his virtue (on it), and considered the correction of evil and the presentation of instruction to be his own duty".