The time-dependent two-dimensional Oldroyd-B fluid flow is investigated in the presence of generalized Fourier's and Fick's laws. The mechanism of heat and mass transport is studied using the Cattaneo-Christov (CC) double diffusion theory, which characterizes the thermal and solutal relaxation factors. In addition, the temperature-dependent thermal conductivity of the fluid is taken into consideration. The modified Fourier's and Fick's approach is used to develop a set of partial differential equations for the flow of an Oldroyd-B fluid as well as thermal and solutal transport. By using the suitable similarity transformations, the governing equations are converted into an ordinary differential equation. To visualize the effects of dimensionless physical constraints on flow and energy transport phenomenon, in the domain [0, ) numerical integration is performed with the help of (Midrich scheme) in Maple software to solve the highly non-linear ordinary differential equations. The effects of various arising parameters can be seen in the graphs of velocities, temperature, and concentration. According to the findings, the thermal and solutal penetration depth declines for the growing values of flow controlling parameter and Lewis number, respectively. The current results are very similar to those found in the literature.