More than two dozen men, women and children had camped in the commercial hub for nearly three weeks after walking 700 kilometres from Quetta.
The latest leg of their journey stretches nearly 750 miles from Karachi, which lies on the Arabian Sea, to the federal capital in the foothills of the Himalayas.
Their hope is to gain public support and pressure the government into freeing relatives who have disappeared allegedly at the hands of security services.
“Our main objective is to secure release of our loved ones but unfortunately we have not received any help from the government so far,” Muhammad Qadir Baloch, leader of the march told AFP on Saturday.
Baloch, 70, who also heads a nongovernmental organisation (NGO), Voice of Missing Baloch Persons, said: “Our next destination is Islamabad where we will finalise our future course of action.”
Tired of waiting for justice – or even news of the fate of their brothers, sons, and husbands – the men and women undertook the unprecedented march Quetta to Karachi.
Rights groups accuse the military and intelligence agencies of kidnapping and killing suspected Baloch rebels before leaving their bodies by the roadside.
According to Human Rights Watch, more than 300 people have suffered this fate – known as “kill and dump” – in Balochistan since January 2011.
The security services deny the allegations and say they are battling a fierce rebellion in the province.
The Supreme Court has also been investigating cases of missing people in Balochistan, issuing warnings to the government to recover these people.