There are several reported cases of various neurological adverse effects following the COVID-19 vaccination globally. Acute vaccine-related encephalopathy and acute disseminated encephalomyelitis (ADEM) are included among them. Here we are reporting three cases of ADEM and one case of acute vaccine-related encephalopathy from Bangladesh, which have a possible association with COVID-19 vaccines. All three ADEM cases were elderly; two cases developed symptoms after receiving the second dose of the Sinopharm vaccine, and another case after receiving the second dose of the Sinovac vaccine. We have treated another case of acute vaccine-related encephalopathy following receiving the Moderna vaccine. The patients had features of encephalopathy, including altered consciousness and convulsions. The ADEM cases had MRI (magnetic resonance imaging) brain findings suggestive of ADEM. The other case had normal MRI findings. All the cases were treated with intravenous corticosteroids with full recovery, except for one ADEM patient, who developed aspiration pneumonia and died. Though it is not possible to conclude that COVID-19 vaccination is the causative agent behind these cases, this case series will help to increase awareness regarding the early detection and treatment of these serious adverse effects.