All the six convicts were found guilty of attempt to murder. The punishment will be announced on Apr 13.
Earlier, 10 people, including a woman, all from Jammu Kashmir, had faced trial in the case.
The court did not found any concrete evidence against four and let them off in the case.
On May 2, 1996, at least 13 people were killed and 39 others injured in the blast that took place in Delhi's Lajpat Nagar.
The accused were arrested soon after the incident after police allegedly tracked the calls made by them to various media houses, claiming responsibility for the terror attack.
They had been booked for various charges including criminal conspiracy and murder.