Gajanejos is a municipality in the province of Guadalajara, in the autonomous community of Castile-La Mancha, Spain. It is a small rural settlement in the central part of the country, within the comarca of La Alcarria.
The municipality is sparsely populated. According to the 2004 census carried out by Spain's National Statistics Institute (INE), Gajanejos had a population of 68 inhabitants, reflecting the low population density typical of many villages in this part of Guadalajara province.