The Republican governor ordered Conservation and Recreation Department Director David Johnson to immediately stop enforcing the ban in a Jan. 14 letter.
Concealed weapon permit holders were already free to carry firearms.
In his letter, McDonnell wrote that the department lacks authority under state law to prohibit firearms being carried in plain view.
To back it up, McDonnell cited an opinion he wrote as attorney general on Sept. 26, 2008, answering an inquiry from then-Sen. Ken Cuccinelli, a Republican who is now attorney general.
Gun control advocate Lori Haas, whose daughter survived a gunshot in the 2007 Virginia Tech massacre, called it bad for public safety and for tourism.