In this paper, we predict the deformation behavior of alloy 690 by explicitly modeling finite thickness grain boundaries within the crystal plasticity framework. This is realized by using a blend of quasi-static tensile experiments, microstructural characterization using scanning electron microscopy, atomistic simulations and crystal plasticity finite element analysis. We begin with material characterization to probe the type of grain boundaries present in the Ni-based alloy 690. Inspired by physically justified multiscale modeling schemes, we then use atomistic simulations within the framework of embedded-atom method to quantify activation parameters for dislocation nucleation from those grain boundaries in Ni bicrystals. The kinetic activation parameters are then passed on to a transition state theory based crystal plasticity model. At this scale, the grain boundaries are explicitly modeled using finite elements and prescribed distinct constitutive parameters obtained from lower scale atomistic simulations. The predictive capabilities of the adopted methodology are demonstrated by capturing the uniaxial tensile behavior of alloy 690 at different temperatures (250C–6000C) (stress-strain curves as well as texture evolution). Our implementation of grain boundaries in crystal plasticity is built upon a standard representative volume element used in most polycrystalline simulations. It is envisioned that this comprehensible approach will provide a compelling platform for unifying many other interface related deformation processes at the mesoscale. Eventually, the demonstrated methodology can expedite in apprehending the structure-property relationships through apt use of physically justified multiscale modeling schemes. © 2021 Acta Materialia Inc.