The week-long congress, held every five years, will end with a transition of power to Vice President Xi Jinping, who will govern for the coming decade amid growing pressure for reform of the communist regime's iron-clad grip on power.
After a top-level murder and graft scandal involving former regional boss Bo Xilai, Hu delivered a stark warning on the need for the party to clean up its act, admonishing that corruption could cause the 'collapse of the party'.
Speaking to more than 2,200 delegates inside Beijing's Great Hall of the People, Hu also positioned the world's second-largest economy for a more assertive international role as he insisted China should be a 'maritime power'.
Heading into the 18th party congress, China has been skirmishing with Japan and other Asian neighbours over a slew of territorial disputes, and flexing its growing military muscles to the disquiet of the United States.
"We must continue to make both active and prudent efforts to carry out reform of the political structure and make the people's democracy more extensive, fuller in scope and sounder in practice," Hu also said.
Without naming Bo, the outgoing communist general-secretary said the party 'must make sure that all are equal before the law'.
Hu also dwelt on the need for China to recalibrate its export- and investment-led growth model after years of breakneck expansion in the economy.
"In response to changes in both domestic and international economic developments, we should speed up the creation of a new growth model and ensure that development is based on improved quality and performance," he said.
The congress will end next week with the installation of Xi as the party's new general-secretary, and he is in line to succeed Hu as state president next March.
But the scandal surrounding Bo, who has been ejected from the party and is now awaiting trial, exposed divisions in the leadership and related back-room jockeying for top positions.
The delegates drawn from the Communist Party's ranks of 82 million members gathered amid intense security around Tiananmen Square for the congress, which runs to November 14, when the new leaders will be presented.
Delegates in the ornate hall, dominated by the party's signature colour of red in the form of flags, carpeting and banners, studiously took notes or followed the text of Hu's speech as he read it out, offering occasional applause.
The party elite appear to have settled on the new leadership line-up in the Politburo Standing Committee, China's highest decision-making body.
The committee will be steered by Xi, 59, who has previously headed some of China's most economically dynamic and reform-minded areas.
"We have overcome numerous difficulties and risks and achieved new successes in building a modern, prosperous society," Hu said in his speech of just over 90 minutes, reviewing the five years since the party's last congress in 2007.
But Xi, the son of a revolutionary hero who has been Hu's heir apparent since 2007, will take over at a challenging time with China facing a rare slowdown in economic growth.
Even the best-informed China-watchers say relatively little is known about Xi and how he will confront challenges facing the nation both at home and abroad, as it increasingly challenges the United States in various arenas.
And while Hu cited the need for some kind of political opening, authorities have taken every precaution to ensure dissenting voices do not intrude on the congress.
Areas of central Beijing near the Great Hall of the People were swarming with police, and authorities have reportedly taken such measures as banning sales of knives and even ping pong balls, for fear they might be used to spread 'reactionary' messages.
Hundreds of activists have been put under house arrest, rights groups say, while taxi drivers have been told to lock their back windows apparently to prevent passengers from throwing out flyers with political messages.
A state-run newspaper published a survey Wednesday suggesting eight out of 10 Chinese in major cities want political reform, adding to mounting calls for change of some sort in how the corruption-ridden Communist Party runs China.
The contrast with how the United States manages its political affairs was laid bare with President Barack Obama's re-election triumph, and did not go unnoticed among commentators on China's wildly popular social media websites.