Dhaka Metropolitan Magistrate Saiful Islam passed the verdict on Wednesday.
The court sentenced them one year jail under section 147 and two-year jail under section 353. The court also fined them Tk 5,000 each.
The 12 convicts are- Anwarul Azim, Haider Ali Babla, Md Alauddin, Shawkat, Md Pervej, Imran Hossain Emu, Sayed Ahmed Rana, Haji Farhad Rana, Arif Hossain Bappy, Fazlul Haque Moni, Haji Md Nazim Uddin and Md Sobhan.
According to the case documents, BNP men carried out subversive activities in Kotwali area of the capital in September, 2018, to create panic among the people.
Police later lodged the case and then filed charge-sheet against 12.