An experimental and theoretical investigation is reported to analyze the relation between the structural and absorption properties of CH3NH3PbI3 in the tetragonal phase. More than 3000 geometry optimizations were performed to reveal the structural disorder and identify structures with the lowest energies. The electronic structure calculations provide an averaged band gap of 1.674 eV, which is in excellent agreement with the experimental value of about 1.6 eV. The simulations of the absorption spectrum for three representative structures with lowest energy reproduced the absorption shoulders observed in the experimental spectra. These shoulders are assigned to excitations having similar orbital characters and involving transitions between hybridized 6s(Pb)/5p(I) orbitals and 6p(Pb) orbitals. The geometries of the three structures were analyzed and the effects of the inorganic frame and the CH3NH3+ cations on the absorption properties were estimated. It was found that both changes in the inorganic frame and the CH3NH3+ cations orientations impact the absorption spectra, by modifying the transitions energies and intensities. This highlights the role of CH3NH3+ cation in influencing the absorption properties of CH3NH3PbI3 and demonstrates that CH3NH3+ cation is one of the key elements explaining the broad and nearly constant absorption spectrum in the visible range. A combined theoretical and experimental study is performed to shed light on the nature of the electronic transitions in the absorption spectrum of the hybrid metal–halide perovskite CH3NH3PbI3. The observed absorption shoulders are assigned by the calculations to different groups of p(I)s(Pb)→p(Pb) transitions involving the inorganic frame. Additionally, it is shown that the orientation of the CH3NH3+ cations has a significant impact on the transition energies and intensities, explaining in part the characteristic absorbance of this material.