The anti-state Pakistani Taliban claimed credit for plotting Thursday's deadly attack in Quetta, capital of Baluchistan province.
Police said slain deputy inspector general Hamid Shakeel was traveling to work from home when a suicide bomber struck his vehicle on a busy road of the city.
The blast wounded at least nine people, including passers-by, with some receiving life threatening injuries, according to doctors.
The slain officer had played a key role in arresting militants and members of separatist groups operating in Baluchistan, senior police official, Naseeb Ullah, told reporters.
A provincial government spokesman, Anwar-ul Haq Kakar, condemned the attack, saying it "demonstrates the sacrifices police is making in the war against terror outfits in Baluchistan."
The largest Pakistani province, which borders Afghanistan and Iran, has long been in the grip of a low-level separatist insurgency.
Islamist and sectarian militants also operate in Baluchistan and often claim attacks on security forces and government installations. The Afghan Taliban is allegedly also sheltering in the province and planning insurgent attacks in Afghanistan.
In recent years Islamic State has emerged as a new threat for the authorities in Baluchistan. The terrorist outfit has taken credit for some recent attacks targeting security forces and worship places of the minority Shi'ite community.
Separately, the Pakistan military reported Thursday one of its soldiers was killed when terrorists fired from across the Afghan border in the remote Rajgal valley of the Khyber tribal district.
Pakistani officials have blamed the "absence' of government control on the Afghan side of the porous frontier for such attacks.