Gulam Haydar Sarwari, the province's deputy police chief, says the attack took place on Sunday night when insurgents targeted a police security post in the remote district of Ab Kamari.
Sarwari says the clash lasted almost four hours before scores of the Taliban attackers were repelled. He says the slain officer was the district police commander. Three other policemen were wounded in the assault.
There was no immediate claim of responsibility from the Taliban, who have been active in Badghis.
The insurgents have stepped up their attacks against both the Afghan and coalition forces across the country.