Jalal Uddin Sarkar, former president of Awami Juba League's Kapasia Upazila unit, was hacked to death on August 17, 2003.
Additional District and Sessions judge Fazle Elahi Bhuiyan announced the verdict in presence of six convicts. Five convicts are still on the run.
Most of the accused reportedly belonged to former premier Khaleda Zia's Bangladesh Nationalist Party (BNP) and its affiliated bodies in Gazipur on the outskirts of Dhaka, bdnews24 reported.
The Court Police's Inspector Md Rabiul Islam said the convicts would be able to appeal against the death penalty in High Court within seven days.