Xi Jinping was also reappointed head of China's Central Military Commission.
Pakistan Prime Minister Shehbaz Sharif on Sunday congratulated China President Xi Jinping for securing a third term as the country's top leader.
Mr Sharif called Xi Jinping's re-election a tribute to his "unwavering devotion" towards the people of China.
"On behalf of the entire Pakistani nation, I congratulate President Xi Jinping on his reelection as CPC General Secretary for the 3rd term. It is a glowing tribute to his sagacious stewardship and unwavering devotion for serving the people of China," tweeted Mr Sharif.
Pakistan's President Arif Alvi, while congratulating his Chinese counterpart, called him a "true friend of Pakistan".
"I extend heartiest congratulations to H.E. Xi Jinping on his reelection as CPC General Secretary, and my best wishes for his health and happiness. He is a true friend of Pakistan and champion for All-Weather Strategic Cooperative Partnership between Pakistan and China," Mr Alvi tweeted.
Xi Jinping was on Sunday re-elected as the General Secretary of the ruling Communist Party of China for a record third five-year term, a privilege only accorded to party founder Mao Zedong.
Xi was also reappointed head of China's Central Military Commission.
His reappointment as party leader is a watershed moment in China's modern history, tilting decisively back towards one-man rule after decades of power-sharing among the elite.
The 69-year-old is now all but certain to sail through to a third term as China's president, due to be formally announced during the government's annual legislative sessions in March.
China is a key economic and political partner of Pakistan, pushing ahead with multi-billion-dollar China-Pakistan Economic Corridor (CPEC). Launched in 2015, CPEC, which connects Gwadar Port in Pakistan's Balochistan with China's Xinjiang province, is the flagship project of China's ambitious Belt and Road Initiative (BRI).