Xi, the uncontested leader of the world's most populous nation, has been heading a pivotal plenary of the ruling party's top figures since Monday in the Chinese capital.
Some 400 members of the powerful Central Committee passed China's resolution on "Major Achievements and Historical Experience of the Party's Centennial Struggle" - only the third ever such resolution in its 100-year history.
The previous two resolutions were issued under former leaders Mao Zedong in 1945, and Deng Xiaoping in 1981.
The lengthy declaration called for upholding "the correct view of party history", said official news agency Xinhua, adding that the party has "written the most magnificent epic in the history of the Chinese nation for thousands of years."
"The Party Central Committee called on the entire party, the entire army and people of all ethnic groups to unite more closely around the Party Central Committee with Comrade Xi Jinping as the core, to fully implement Xi Jinping's new era of socialism with Chinese characteristics," the Xinhua readout read.
This year's closed-door plenum paves the way for the 20th party congress next autumn, at which Xi is widely expected to be handed a third term in office, securing his position as China's most powerful leader since Mao.
Analysts say the resolution will help Xi shore up his grip on power by setting in stone his vision for China and diminishing the role of previous leaders.
The "thought" of Xi "is the epitome of Chinese culture and soul," the text reads, saying that his presence at the "heart" of the ruling party "is of decisive importance... to promote the historic process of the great renewal of the Chinese nation."
State TV's evening news broadcast said Xi's resolution was of "wide-ranging historical significance", showing footage of Xi addressing rows of delegates in the Great Hall of the People in front of red flags and the Communist symbol.
The first such resolution on the party's history passed under Mao helped him cement his authority over the Communist Party four years before it seized power.
The second, adopted under Deng, saw the regime adopt economic reforms and recognize the "mistakes" of Mao's ways.
Unlike the 1981 resolution, Thursday's communique completely glosses over the widespread turmoil of the Cultural Revolution, a devastating period of political upheaval in the 1960s and 70s.
Instead it refers to the period as one of "socialist revolution and construction."
Chairman Mao is mentioned seven times in the document, while Deng only five times.
In comparison, Xi Jingping is mentioned 17 times.
Xinhua this week described Xi as "undoubtedly the core figure in charting the course of history."