The incident took place in the 12th police district of Herat city leaving the religious cleric Sheikh Azizullah Najafi critically wounded.
A local security official said Sheikh Najafi succumbed to his injuries after he was taken to hospital following the attack.
The official speaking on the condition of anonymity said Sheikh Najafi had received multiple shots in his head.
Sheikh Najafi was a prominent religious cleric who was also a member of the provincial council.
No group including the Taliban militants has so far claimed responsibility behind the incident.
This comes as another prominent religious cleric Mir Farooq Hussaini was shot dead in a similar attack in Herat province earlier this year.