Officials in the US state of Tennessee said the DNA matched that of Anthony Quinn Warner, 63.
The FBI said there was no indication of additional suspects and that it was too early to suggest a motive.
The blast outside a telecoms office disrupted communications systems in Tennessee and four other states.
During a press conference on Sunday, federal investigators said they believed that Warner, who worked in IT and had extensive experience with electronics, was the sole individual responsible for the blast and had died at the site.
They said the blast was probably deliberate, and that it was Warner's remains discovered at the scene.