The consolidation also affects about 110 jobs at Exxon Mobil offices in Akron, Ohio, which are also being moved to Houston.
Exxon Mobil's Fairfax campus is a remnant from the days when Mobil Corp. was headquartered in the county, before it merged with Exxon in 1999.
Fairfax County Economic Development Authority President Gerald Gordon declined to say Wednesday whether the county and state put together an incentive package seeking to retain the company. He said Exxon Mobil had been studying a campus consolidation for several years.
"Exxon Mobil, and Mobil before the merger, has been a major employer in Fairfax County and an excellent corporate citizen, so its departure will be a big loss but not devastating because this is an economy with more than 600,000 jobs," Gordon said. "We thank the company for its contributions to the county economy and quality of life."
Exxon Mobil is one of the top 20 employers in the county of 1 million residents, according to the authority.
Gordon said his office is working to find another employer to occupy the site.
In a press release, Exxon Mobil said the relocations will begin in 2014 and conclude by 2015. Spokesman David Eglinton said the company does not expect any significant staffing reductions as a result of the move.
The Fairfax campus has been headquarters for Exxon Mobil's refining operations. The campus now being built in Houston is expected to accommodate 10,000 employees.