Camal Ali was arrested on March 17 along with his band's bass player, Natiq Kamilov, after he insulted President Ilham Aliyev's late mother during a performance at an opposition youth rally.
The event's organizer, Etibar Salmanli, was also arrested.
The three were later sentenced to up to 10 days in jail on charges of hooliganism.
During the hearing on March 21, Ali reiterated claims that he was subjected to extreme violence and denied access to his lawyer for four days while in police custody.
"They beat me and I am sure they will do the same later on. They were beating the souls of my feet with truncheons," he said.
Salmanli and Kamilov also said they were beaten in jail and forced to sign papers that used profanity against Aliyev.