US Attorney Patrick Ryan announced that the government would seek the death penalty - by lethal injection - in the bombing, the most deadly terrorist attack in US history. No trial date or site have been chosen.
In exchange for his testimony against Mr McVeigh and Mr Nichols, their friend Michael Fortier was indicted on lesser charges of gun trafficking across state lines and knowing of the conspiracy but concealing his knowledge from investigators. The charges against him carry a maximum sentence of 23 years in prison.
The federal grand jury indictments, handed down in Oklahoma, alleged that Mr McVeigh, 27, and Mr Nichols, 40, planned and constructed the 4,800lb bomb. Specifically Mr McVeigh is charged with planting and detonating the device. Mr Nichols is believed to have bought the diesel fuel used in the construction of the fertiliser bomb.
The two are said to share a deep hatred of the federal government and have been linked to right-wing militias. Prosecutors say they became disillusioned with the "American dream" and decided to take matters into their own hands.
The indictments keep open the possibility that others may have been involved in the bombing and allow for further indictments against other conspirators as yet unknown. Eight of the 11 charges against Mr McVeigh and Mr Nichols allow for a separate prosecution for people killed outside the federal building.
Attorney General Janet Reno, speaking in Washington, said charges previously lodged against Mr Nichols's brother, James, for possession of "illegal destructive devices" were being dropped. Mr McVeigh's sister, Jennifer, and Mr Fortier's wife, who also allegedly knew of the conspiracy, are to testify for the prosecution in exchange for immunity .
Ms Reno said the bombing investigation would continue, but "we have charged everyone involved we have evidence of at this point''. Most of the investigators' leads "have been pursued and exhausted,'' she added.
The investigation involved hundreds of federal, state and local law enforcement officers and was given an early break when Mr McVeigh was stopped for a traffic offence after the bombing.
At a news conference in Oklahoma City, investigators from the FBI and Bureau of Alcohol, Tobacco and Firearms refused to elaborate on the evidence they will present at trial. "We're not interested in trying this case in the media," one official said.
Mr Fortier, 26, has struck a deal which will elevate the government's case from one built primarily on scientific and circumstantial evidence to one in which Mr Fortier will give a detailed account of the conspiracy. Mr Fortier, the authorities said, admitted to casing the building with Mr McVeigh.