The accurate prediction of failure mechanisms in fastening and anchoring systems remains a significant challenge in computational structural mechanics. In such applications, the surrounding concrete is subjected to complex multi-axial stress states and non-proportional loading paths, often resulting in mixed-mode failure patterns that are challenging for conventional constitutive models for concrete to reproduce. This contribution addresses these challenges by presenting a novel gradient-enhanced extension of the Microplane M7 model. While the original M7 model by Caner and Bažant (2013) offers a sophisticated description of the triaxial behavior of concrete, its local formulation suffers from mesh dependency in the softening regime. We propose an implicit gradient-enhanced extension that introduces an internal length scale, ensuring mesh-objective results while preserving the inherent anisotropy of the material response. The performance of the proposed model is assessed using three-dimensional implicit finite element simulations of benchmark tests subjected to shear and mixed-mode loading. Its predictive capability is evaluated through simulations based solely on standard material parameters and compared against two established nonlocal constitutive models: the gradient-enhanced version of the Concrete Damage-Plasticity model (Grassl and Jirásek, 2006; Poh and Swaddiwudhipong, 2009) and the gradient-enhanced Microplane Damage-Plasticity model (Zreid and Kaliske, 2018). Finally, the proposed model is applied to a challenging simulation of an anchor pull-out test. The results demonstrate the ability of the gradient-enhanced M7 model to capture complex curved mixed-mode crack patterns and to accurately reproduce load-displacement responses across several benchmark tests.