Concrete, a widely used construction material, faces challenges related to long-term durability and environmental resilience, often due to inadequate microstructural integrity. This study investigates the synergistic effect of hybrid nano-modification using nano-kaolin (NK) and nano-zeolite (NZ) as partial cement replacements to enhance concrete’s mechanical and durability properties. Concrete mixes were prepared with varying dosages of NK (1–4%) and NZ (1–4%), both individually and in combination. The study evaluated compressive, flexural, and split tensile strength, water absorption, acid resistance, thermal stability, and bond strength. Microstructural analysis was performed using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDAX), and Fourier Transform Infrared Spectroscopy (FTIR). Among the mixes, the optimal combination of 3% NK and 2% NZ significantly improved performance. Specifically, the compressive strength increased by 18.5% (56.7 MPa), flexural strength by 15.7% (6.84 MPa), and split tensile strength by 9.3% (3.89 MPa) compared to the control mix. Water absorption decreased by 19.8%, and bond strength improved by 12.8% (8.44 MPa). The 3% NK + 2% NZ mix also showed superior acid resistance, retaining 71.5% strength under sulfuric acid exposure, and exhibited enhanced thermal stability, withstanding up to 900 °C (compared with control mix). Other mixes with varying NK and NZ dosages showed moderate improvements, but the 3% NK + 2% NZ combination consistently outperformed the others in terms of strength, durability, and resistance to environmental factors. These results demonstrate that hybrid nano-modification using NK and NZ can provide a sustainable, high-performance solution for concrete, improving its durability and structural integrity, particularly in aggressive environments. © 2025 Elsevier B.V., All rights reserved.