In continuous search for a better method of estimating the population mean in double sampling techniques, with advantageous properties than some existing ones and to address the problem of efficiency thereon, a generalized efficient family of ratio estimator of population mean under double sampling techniques is suggested using information on a single supplementary variable. Members of the suggested family of estimator were obtained by modifying the values of the scalars associated with the suggested estimator. These estimator and its members were then transformed to an expanded form, from where their properties such as Biases, relative biases, Mean Square Errors (MSEs), and Optimal Mean Square Errors (OMSEs) were derived to the second order of Taylor series approximation. Theoretical underpinnings and conditions for measuring efficiency of an estimator over its competitor estimators were established and validated with some natural population data sets. The results showed that the generalized efficient family of ratio estimators in double sampling techniques produced smaller MSEs which is an indicator of appreciable gain in efficiency and dominance over some existing ratio estimators and were therefore deemed to provide a better substitute whenever priority is placed on efficiency.