BJP Tamil Nadu unit General Secretary V Ramesh was hacked to death by unidentified assailants near his house on Friday night, police said.
The 52-year-old Ramesh alias Auditor Ramesh was attacked with sharp-edged weapons and he died on the spot, they said.
The identity of the assailants and the motive for the attack were under investigation, police added.
Ramesh is the second senior party functionary in Tamil Nadu to be murdered in the last nine months.
BJP state medical wing secretary Dr V Aravind was killed in front of his clinic in Vellore by a gang in October, 2012.