Gilmore never had any momentum in the race, did not qualify for any of the Republican prime-time debates and also missed the cut for several of the undercard debates.
He received only 12 votes in the Iowa caucuses, placing him dead last. He won 133 votes in the New Hampshire primary.
My campaign was intended to offer the gubernatorial experience, with the track record of a true conservative, experienced in national security, to unite the party." Gilmore said in a statement. "My goal was to focus on the importance of this election as a real turning point, and to emphasize the dangers of continuing on a road that will further undermine America's economy and weaken our national security."
Gilmore said he will support the eventual GOP nominee.
"I will continue to express my concerns about the dangers of electing someone who has pledged to continue Obama's disastrous policies," he said. "And, I will continue to do everything I can to ensure that our next President is a free enterprise Republican who will restore our nation to greatness and keep our citizens safe."
Gilmore became the 17th hopeful to enter the 2016 Republican primary race when he filed paperwork with the Federal Election Commission in late July, only a week before the first GOP debate. It was his second bid for the party's presidential nomination. He also ran, briefly, in 2007 before dropping out over the summer.
A former counter-intelligence agent, Gilmore served as governor of Virginia from 1998 to 2002 -- after stepping down as state attorney general to focus on his campaign -- and spent 2001 as the chairman of the Republican National Committee.
"I've been looking for someone to enter the race committed to my belief that America's economic and national security is increasingly at risk," he said last year in a video announcing his candidacy. "But I haven't seen a response from anyone that makes me certain about their knowledge or solutions to the threats facing our nation."
Gilmore never raised a significant amount of money. In 2015, he brought in only $90,000, according to FEC figures, and lent his campaign an additional $124,000.
Even Donald Trump, when asked about Gilmore by The New York Times last August, was left nearly speechless.
"Him," Trump said, "I don't know."
Ohio Gov. John Kasich, who finished second in New Hampshire, praised Gilmore via Twitter. "@Gov_Gilmore felt the call to serve in both our military and elected office. That courage should be honored. Best of luck, governor! -John"