Phenothiazine-based donor–π–acceptor (D–π–A) emitters, NTPH and NTPCF, were developed as multifunctional materials exhibiting dual conformations with distinct photophysical properties. Structural studies reveal quasi-axial and quasi-equatorial conformers that enable tunable fluorescence and thermally activated delayed fluorescence (TADF). NTPCF shows green emission, while NTPH displays cyan emission and orange TADF arising from conformational switching with small singlet–triplet energy gaps. Mechanoresponsive behavior enables reversible color modulation, highlighting applications in sensing and anticounterfeiting. Solution- processed OLEDs based on NTPCF achieve luminance up to 8400 cd m⁻² and enable single-molecule white OLEDs, delivering both cool and warm white emission through controlled doping strategies.