The High Court bench Justice Sheikh Abdul Awal and Justice Bhishmadev Chakrabortty passed the order after hearing on their appeals.
Lawyers Mohammad Arsadur Rouf and Jamilur Rahman stood for the IGPs.
Arsadur Rouf said that now there is no bar to their release from jail.
Earlier on January 13, the High Court accepted the appeals of 44 convicts, including 18 condemned ones, for hearing in the August 21 grenade attack cases.
On October 10, a speedy trial tribunal sentenced 19 people, including former State Minister for Home Lutfozzaman Babar and former Deputy Minister for Education Abdus Salam Pintu, to death while 19 others, including BNP acting Chairman Tarique Rahman, to life imprisonment in two cases filed over the August 21 grenade attack on an Awami League rally in the capital in 2004.
Besides, 11 people were awarded different jail terms in the sensational cases.
Among the convicts, former Inspectors General of Police (IGP) Ashraful Huda and Shahudul Haque were sentenced to four years jail and fined Tk 50,000 for harbouring the offenders under two separate sections of the case.