Two geometrically constrained Cu(I)-monophenanthroline complexes were investigated spectroscopically to study the effects that ligand constraints have on the excited-state dynamics of copper-phenanthroline complexes. Room temperature steady-state absorption and emission spectra were obtained for the two complexes and time-resolved fluorescence spectra of the Cu(I) complexes in dichloromethane were collected using time-correlated single photon counting. The effect of the ligands on the excited-state dynamics of the two complexes was monitored by femtosecond pump-probe spectroscopy. Transient absorption spectroscopy with femtosecond resolution enabled the direct observation of the relaxation in the photoinduced metal-to-ligand charge-transfer (MLCT) state of the complexes, where the tetrahedral Franck-Condon Cu(II) complex undergoes vibrational relaxation to form the energetically favorable square planar conformation. The flattening relaxation was found to have two lifetime components of 8-10 and 40-52 ps for the rearrangement of the 1: 1 copper-phenanthroline complexes, which is likely related to the flattening around the metal center and the subsequent rearrangement of the methylphenyl-pyrazole backbone according to the more planar conformation, respectively. The excited-state dynamics correlate with the measured UV-vis absorption and emission properties of the complexes and are discussed in the light of steric constraints on the photophysics of the Cu(I)-monophenanthroline complexes. The higher quantum yield, longer emission lifetime, and faster relaxation dynamics of the dimethyl-substituted pyrazole-based complex compared with the unmethylated analogue agree with the steric arguments that in a 1: 1 ligand framework, addition of alkyl substituents in the ligand hinders the flattening relaxation. This investigation is complementing photophysical studies performed over the past two decades on the effect of substitutents on the photophysics of the structurally related 1:2 Cu(I)-phenanthroline complexes by providing a time-resolved spectroscopic observation of the excited-state relaxation in geometrically constrained Cu(I)-phenanthroline complexes following the photoinduced MLCT.