Dylann Roof told a judge he plans on calling no witnesses when jurors decide next week decide whether he will face life in prison or the death penalty.
Roof, 22, was found guilty on 33 counts, including federal hate crimes, earlier this month.
His 2015 attack, carried out during a Bible study session, shocked the US.
Among his victims were pastors, recent graduates, librarians and coaches.
Roof later told police he wanted to start a race war with his attack on the Emanuel African Methodist Episcopal Church, in Charleston, and he was photographed holding the Civil War battle flag, which to many is a symbol of hate.
He is acting as his own lawyer in the final stage of his trial, after dismissing his defence team.
But District Judge Richard Gergel advised Roof to talk to his grandfather, who is a lawyer, and other family members one last time before the trial begins.
Judge Gergel added Roof can change his mind and bring back his attorneys up until opening statements next week.
Serial killer Ted Bundy, Washington-area sniper John Allen Muhammed and Fort Hood attacker Nidal Hasan also acted as their own lawyers, but ended up with death sentences.
According to the Post and Courier, the prosecution has a list of more than 30 possible witnesses to present.
Sources : the post and Courier and BBC World .