"Despite all the odds, completion of the term is an extraordinary and historic achievement," Prime Minister Raja Pervez Ashraf said in an address to the nation Saturday.
Pakistan has been in existence for 65 tumultuous years and has been under the rule of military juntas for nearly half that time, CNN said. Ashraf called Sunday's anniversary a victory for democracy.
A caretaker government will be installed in Pakistan in the coming weeks as part of the run-up to the first elections in five years.
Ashraf's Pakistan Peoples Party was voted into power in 2008 just weeks after PPP leader Benazir Bhutto was assassinated. The PPP displaced the unpopular Pervez Musharraf, but CNN said voters had little confidence the PPP would be able to stabilize the economy and political situation.