Shahpoor Khan led a tribal militia against Taliban insurgents in the Mamoond district of Bajaur, one of the seven districts in Pakistan's tribal belt where US officials say al-Qaeda fighters are operating.
He was killed while returning home at the start of the Eid al-Adha festival when an improvised explosive device went off in his hometown of Badan.
Mr Kahn had been returning home after saying special Eid prayers in a mosque.
Some people in Bajaur, which borders Afghanistan, celebrate the start of the festival one day ahead of the festivities in Pakistan, the official said.
Mr Khan, who was in his 40s, was the successor to Malik Rehmatullah who was killed in a suicide attack at a mosque last year along with around 20 people.
Islamist militants have stepped up attacks in Bajaur since Pakistan launched a major offensive designed to crush the Taliban in its South Waziristan headquarters last month.
Insurgents' most popular targets in Pakistan are security officials, government installations and tribesmen allied against the Taliban.
Officials say the aim of the surge in unrest is to distract the army's attention from South Waziristan, where around 30,000 troops have been pressing the US-endorsed air and ground assault for six weeks.
Violence has continued to blight Bajaur despite a six-month military offensive that the army declared a success last February.
Hundreds of extremists carved out safe havens in Pakistan's semi-autonomous tribal areas after US-led troops ousted the Taliban regime in neighbouring Afghanistan in late 2001.
