Newington is a census-designated place (CDP) in affluent, suburban Fairfax County, Virginia, United States. The population was 12,943 at the 2010 census. The 2010 census showed a significant decrease after half the population was split off to the newly created Newington Forest CDP.While the ZIP code for Newington is 22122, this is only for delivery points within the post office itself. Homes and businesses in the CDP have Springfield or Lorton street addresses.