Khan was found guilty of not declaring money earned from selling gifts he received in office.
He denies the charges and says he will appeal.
After the verdict, Khan was taken into custody from his home in Lahore.
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In a pre-recorded statement on X, formerly known as Twitter, he told his supporters: “I have only one appeal; don’t sit at home silently.”
The former cricketer-turned-politician, 70, was elected in 2018 but was ousted in a no-confidence vote last year, after falling out with Pakistan’s powerful military.
Khan is facing more than 100 cases brought against him since his removal—charges he says are politically motivated.
Saturday’s verdict centred on charges that he incorrectly declared details of presents from foreign dignitaries and proceeds from their alleged sale.
The gifts, reported to be worth more than 140 million Pakistani rupees ($635,000; £500,000), included Rolex watches, a ring, and a pair of cuff links.
Imran Khan’s lawyer, Intazar Hussain Panjutha, told reporters that the trial had been conducted by “a kangaroo-type court,” in which, “the accused was never allowed to defend himself.
He added, “As a consequence of today’s conviction, he has been barred from taking part in politics for five years.”
Panjutha said,
“But if the sentence and the conviction are suspended, as we are hoping by the superior courts, he will then be able to come back to politics.”
Khan will be sent to Adyala jail, a central prison in the city of Rawalpindi, south of Islamabad.
For months, he had avoided arrest, with his supporters at times fighting pitched battles with police, to keep him out of custody.
In May, Khan was arrested for not appearing in court as requested.
He was then released, with the arrest declared illegal.
Since then, his party has been under intense pressure from the authorities.
(Editor: Ifeanyi Mark)
