The flexural behavior of CFRP (carbon fiber reinforced polymer)-reinforced blast-damaged UHTCC (ultra high toughness cementitious composite) beams was investigated in this study. Seven UHTCC beams with different fiber types and stirrup spacings were prepared. The experimental procedure was conducted as follows: mid-span contact explosion simulation (using 120 g emulsion explosive), CFRP strengthening, and four-point bending tests. Through these tests, the failure modes, load-deflection relationships, and strain development in UHTCC and CFRP were systematically analyzed. The results indicate that the failure mode is shifted from flexural failure to shear-compression failure with the increase of stirrup spacing. The incorporation of fibers significantly improves the flexural capacity (with steel fibers exhibiting the highest enhancement of 11.68%), but the yielding stage is shortened simultaneously. In addition, fibers increase the ultimate strain of UHTCC (6.69% increase achieved by steel fibers) and the debonding strain of CFRP (7.73% increase achieved by PE fibers). However, the strain capacity is found to decline with larger stirrup spacings, and the most severe deterioration is observed in beams with steel fibers (reaching 46.40%). Finally, a proposed flexural capacity model is verified to agree well with the experimental data.