According to local news channels, shots were fired near the convoy of Mr Khan, 70, as he led a protest march in Wazirabad, in the eastern Punjab province.
The former prime minister was doing so in a bid to call for snap elections after being removed from office in April.
Mr Khan was soon rushed away from the scene and taken to hospital. According to his supporters, he suffered a gunshot wound just above his foot although it was later confirmed as a minor injury. One of his supporters was killed by the gunman.
"A man opened fire with an automatic weapon. Several people are wounded. Imran Khan is also injured," party official Asad Umar said at the time.
Officials later said that Mr Khan was safe and had been taken to hospital.
A suspect was immediately arrested at the scene and police later released a video of him in custody, allegedly confessing to the shooting and saying he acted alone.
It was not clear under what conditions he made his statement in which he said “Only Imran Khan was my target."
District police officer Ghazanfar Ali said one person was killed and nine others were hurt in the attack.
The shooting was an "assassination attempt," a spokesman for Mr Khan’s Tehreek-e-Insaf party said. He added that "it was an attack on the whole of Pakistan" and vowed that the people would avenge it.
The attack has raised fresh concerns about growing political instability in Pakistan since Mr Khan's ousting in a no-confidence vote in Parliament in April.
Commenting on the incident, Canadian prime minister Justin Trudeau: “The attack on Imran Khan and his supporters is completely unacceptable, and I strongly condemn this violence. It has no place in politics, in any democracy, or in our society.
“I’m wishing a speedy recovery to Imran and all who were injured today.”
I'm deeply concerned by these reports from Pakistan. No political leader should ever face violence or intimidation. My prayers are with Imran Khan and the people of Pakistan at this extremely distressing timehttps://t.co/VhJvRpF1PT
— Mayor of London, Sadiq Khan (@MayorofLondon) November 3, 2022
Since being removed from office, Mr Khan has held a series of speeches at locations across the country. At the time of the incident, he was six days into a march from Lahore to Islamabad.
Among the wounded was Faisal Javed, a politician from Tehreek-e-Insaf. In a video statement, with bloodstained clothes, he said the attack will not stop Mr Khan's protest march to Islamabad.
Prime Minister Shehbaz Sharif condemned the shooting and ordered the interior minister to seek an immediate investigation.
Mr Sharif's government said, however, there will be no early vote and the next election will be held in 2023, according to schedule.
Mr Khan came to power in 2018, promising to break the pattern of family rule in Pakistan.
The parliament's no-confidence vote in April that ousted Mr Khan capped months of political turmoil and a constitutional crisis that required the Supreme Court to intervene following his near four years in office.