However, he also said that the global super power would not be told what to do by anyone. Late leader Deng Xiaoping's campaign of "reform and opening up" began four decades ago.
The resulting growth has made China the second largest economy in the world.
Mr Xi said despite this growth, China would "never seek global hegemony" and also highlighted its contributions towards a "shared future for mankind".
Critics say China continues to crack down on political dissent and take a hard stance against any of ethnic or social instability.
Also in recent years, the country has struggled with mounting debt and slowing economic growth.
Asserting Chinese strength
Mr Xi spent much of his lengthy speech listing examples of China's progress over the past decades, praising them as "epic achievements that moved heaven and Earth".
He said that given its success, "no-one is in a position to dictate to China what to do or not to do".
At the same time, he stressed what he described as Chinese efforts to work towards the greater global good, saying Beijing was a "promoter of world peace," a "defender of international order" and holding "a leading role in dealing with climate change".
China's economic reform was initiated by then leader Deng Xiaoping in 1978 and the programme was ratified on 18 December that year.
The reform path turned the country away from the old style communism of Mao Zedong when collectivisation had led to an impoverished and inefficient economy.
The transformation focussed on agricultural reform, private sector liberalisation, industry modernisation and opening to international trade.
Xi Jinping described the reforms as a "break from the shackles" of previous mistakes.
China's reform process was kicked off in 1978
He said the last 40 years had been a "quantum leap for socialism with Chinese characteristics," driving China's "great rejuvenation in modern times".
The Chinese president made no direct mention of the current trade dispute with the US but stressed his country's contribution to economic globalisation and international order.
The row with the US has led to a spiral of tit-for-tat tariffs with potentially serious economic consequences for both China and the US should they fail to resolve the dispute.
No political changes
Despite the economic reforms, the past decades have not brought change to China's rigid one-party system of communist rule.
China's president gave his Tuesday speech in the Great Hall of the People in Beijing's Tiananmen Square, where calls for political reforms were brutally crushed by the military in 1989.
In his address, Mr Xi reiterated his belief in strengthening the party leadership and praised Beijing's crackdown on corruption. Critics say the rule of Xi Jinping has been marked by an ever intensifying crackdown on political dissent.
Authorities have also been accused of excessive control of religious groups and brutally repressing the Muslim Uighur minority in Xinjiang province.
Xi Jinping is widely seen as China's most influential leader since Mao Zedong. In 2017, he cemented his power, enshrining his political views in the constitution.