Excellent stability is an essential premise for organic diradicals to be used in organic electronic and spintronic devices. Herein, we attach two tris(2,4,6‐trichlorophenyl)methyl (TTM) radical building blocks to the two sides of perylene bisimide (PBI) bridges and obtain two regioisomeric diradicals (1,6‐TTM‐PBI and 1,7‐TTM‐PBI). Both of the isomers show super stability rather than the monomeric TTM under ambient conditions, due to the enlarged conjugation as well as the electron withdrawing effects from the PBI bridges. The diradicals show distinct and reversible multi‐step redox processes, and the spectroelectrochemistry investigation reveals the generation of organic mixed‐valence (MV) species during reduction processes. The two diradicals have singlet ground states, very small singlet−triplet energy gaps (ΔES‐T) and a pure open‐shell character (with diradical character y0 = 0.966 for 1,6‐TTM‐PBI and 0.967 for 1,7‐TTM‐PBI). This work opens a window to develop very stable diradicals and offers them opportunity of further applications in optical, electronic and magnetic devices.