"This will be the first government that will not carry out any political victimization," Khan, 65, said in a televised speech from his house near the capital Islamabad on Thursday as a partial count gave him a commanding lead.
"God has given me a chance to come to power to implement that ideology which I started 22 years ago," he said, adding, "We were successful and we were given a mandate."
The cricket legend called for "mutually beneficial" relationships with Pakistan's on-off ally the United State.
He also offered an olive branch to arch-foe India and said New Delhi and Islamabad should resolve the long-simmering dispute over Kashmir.
Results were still being tallied after supporters of Nawaz Sharif claimed that there were problems with the vote count and the process was an assault on democracy.
With about half the votes counted from Wednesday's elections, Khan's Pakistan Tehreek-i-Insaf (PTI), or Pakistan Movement for Justice, leads ahead of rivals, the country's election commission said.
Sharif's Pakistan Muslim League-Nawaz (PML-N) and rival Pakistan People’s Party (PPP) both claimed that their monitors in many voting centers were either kicked out during counting or had not received the official notifications of the precinct's results.
