The attack on Tuesday at a campaign event organised by the Awami National Party (ANP) also wounded at least 65 people, according to the local police chief.
Bilour was a provincial assembly candidate for the July 25 general elections. His father, Bashir Bilour, also a prominent ANP politician, was killed by a suicide bomber in 2012.
Police said the bomber struck when Bilour was about to address some 200 supporters.
“According to our initial investigation, it was a suicide attack and Haroon Bilour … was the target,” police official Shafqat Malik told AFP news agency.
There was no immediate claim of responsibility for Tuesday’s attack.
Al Jazeera’s Kamal Hyder, reporting from Pakistan’s capital, Islamabad, said the attack took place at a crowded and narrow area moments after Bilour’s arrival at the scene.
“As he got out of the vehicle, the suicide bomber is said to have got within striking distance detonating his device,” he said.
Local television channels broadcast live scenes of ambulances arriving at the site and rushing victims to the hospital.
Some people were seen crying.
Bilour belonged to an influential political family in the Khyber-Pakhtunkhwa province, of which Peshawar is the capital.
The ANP was the main target of Taliban attacks in the 2013 election.
The bombing came hours after the Pakistan military spokesman warned about security threats ahead of the national elections.
“Pakistan has seen a relative calm and that of course has encouraged the politicians to come out. But the attack today showed that this is going to be a tense affair,” said Al Jazeera’s Hyder.
“It is going to affect the campaigning for many of the political parties.”
SOURCE: AL JAZEERA AND AGENCIES