The party unanimously passed the amendment to include "Xi Jinping Thought on Socialism with Chinese Characteristics for a New Era" as one of its guiding principles at the end of its week-long congress.
It will announce its new Standing Committee, the apex of power in the country, around midday on Wednesday. The current committee is made up of seven people.
Whether Xi was able to have his name "crowned" in the party constitution had been seen as a key measure of his power, elevating him to the level of previous leaders exemplified by Mao Zedong Thought and Deng Xiaoping Theory.
Xi's more recent predecessors, Jiang Zemin and Hu Jintao, both had the party constitution amended to include their guiding thoughts, but without their names directly attached.
Jiang had his "Three Represents" embracing private entrepreneurs written in, while Hu, Xi's immediate predecessor, had his economic doctrine of "scientific development" included.
Xi has rapidly consolidated power since assuming party leadership in late 2012 and then the presidency the next year.
The party gave Xi the title of "core" leader a year ago, a significant strengthening of his position ahead of the congress, which is held once every five years.