Structural transformation in hybrid halides is an attractive way to modulate and improve their optical properties. Following newly reported monovalent-metal-based organic-inorganic chlorides [N(CH3)4]MCl2 (M = Ga+, In+), their bromide analogues [N(CH3)4]MBr2 (M = Ga+, In+) were subsequently synthesized. Impressively, their structure transforms from noncentrosymmetric P4̅21m space group for chlorides to centrosymmetric P42/m space group for bromides. As the halogen changes, the (MBr2)- units are partially rotated along the c-axis, which can be attributed to the difference in the anion radius and H-bond interactions between host networks and guest molecules. In addition, the tunable electronic structure and optical anisotropy in this family are also presented. This work provides a typical example for exploring new asymmetric and symmetric organic-inorganic hybrid halides as appliable photoelectric functional materials.