Sheikh Ibrahim Zakzaky left Nigeria on Thursday for medical purposes the day after his release by the Kaduna State High Court.
Doctors who examined Zakzaky sent him abroad for better medical treatment after finding large amounts of lead in his body due to gunshot wounds.
Medical experts say Zakzaky's specialized treatment is only available outside Nigeria.
Kaduna State High Court on Wednesday acquitted and released the leader of the Islamic Movement in Nigeria and his wife after six years in prison.
Kaduna State High Court judge said the government had failed to provide evidence of eight charges against Zakzaky and his wife.
Sheikh Ibrahim Zakzaky and his wife were arrested on December 13, 2015, during a Nigerian military raid on a Husseiniyah in Zaria.