David Edgar Herold was born on June 16, 1842, in Maryland, the sixth of eleven children to Adam George Herold and Mary Ann Porter. His father served as the Chief Clerk of the Naval Storehouse at the Washington Navy Yard for over two decades, providing the family with a comfortable lifestyle. They resided in a substantial brick house at 636 Eighth Street SE in Washington, D.C., near the Navy Yard.

Herold received his education at several institutions, including Gonzaga College High School, Georgetown College, Charlotte Hall Military Academy, and Rittenhouse Academy. In 1860, he earned a certificate in pharmacy from Georgetown College and subsequently worked as a pharmacist's assistant and a clerk for a doctor. An avid hunter, Herold became well-acquainted with the Maryland countryside. He met John Surratt while attending Charlotte Hall Military Academy, and through Surratt, he was introduced to John Wilkes Booth in December 1864.

Initially, Herold and a group of co-conspirators, including Booth, plotted to kidnap President Abraham Lincoln but later shifted their plan to assassination. On the night of April 14, 1865, Herold guided Lewis Powell to the home of Secretary of State William H. Seward. While Powell entered the Seward residence and attacked the Secretary, Herold waited outside with a horse. Frightened by the commotion, Herold fled, leaving Powell behind.

Herold then rendezvoused with Booth, who had just assassinated President Lincoln at Ford's Theatre. The two men fled through Maryland, stopping at the home of Dr. Samuel Mudd, who treated Booth's injured leg. They continued their escape, receiving assistance from Confederate sympathizers, and eventually reached the farm of Richard Garrett in Virginia.

On April 26, 1865, Union soldiers surrounded the barn where Booth and Herold were hiding. Herold surrendered, but Booth refused and was shot dead by Sergeant Boston Corbett.

Herold was tried by a military tribunal and, despite his defense attorney's argument that he was feeble-minded and under Booth's influence, was convicted and sentenced to death. He was executed by hanging on July 7, 1865, alongside fellow conspirators Mary Surratt, Lewis Powell, and George Atzerodt.