This study investigates the impact of recycled carbon fibers (RCF) on the mechanical properties of high-strength concrete. RCFC is produced with diverse RCF contents and lengths for evaluating compressive and flexural properties. Analysis includes load-deflection curves, flexural strength, peak deflection, initial crack parameters, and the flexural toughness index under bending. SEM examination reveals RCF's toughening mechanism and microstructure within concrete. RCF inclusion significantly boosts compressive and flexural strengths, with enhancements of 4.77% to 19.41% and 2.40% to 31.40%, respectively. The curves show a nonlinear trend with an ascending phase and plateau. RCF increases load and deflection, with complex effects on strength and toughness. SEM images show RCF as a key element in a 3D fiber network, enhancing crack resistance and toughness until fiber extraction or breakage.