Prosecutors in Wichita Falls say sentencing dates have not been set for the men, who face maximum five-year terms over contracts for Sheppard Air Force Base.
Prosecutors on Friday announced the guilty pleas by John Torrance Gilmore III and Larry Thomas Ballard, both of Wichita Falls, and James Carmon Freeman of Vernon and Miguel Angel Hughes of Fort Worth.
A federal grand jury in July indicted the two government workers and two businessmen. All pleaded guilty last week to conspiring to defraud the U.S. and conspiring to unlawfully obtain sensitive source information.
Gilmore and Ballard worked in the base's civil engineering department. Hughes and Freeman owned construction firms.