Isometrically dibromated thienyl-containing aza-BODIPYs CDB-1 and BDB-2 with potential use as photosensitizers (PSs) were successfully prepared and their photophysical properties were fully characterized. Singlet oxygen generation experiments were also performed. In this regard, PS CDB-1 was found to be more effective and had about two-fold rate enhancement compared to PS BDB-2. DFT and TD-DFT calculations helped to provide insights into the distinct intersystem crossing (ISC) processes observed for CDB-1 and BDB-2.