To investigate plasmon-assisted isomerization of azobenzene derivative, we designed a new formulation containing photochromic (azobenzene modified with glycine -AzoGly, see Scheme S1 and Figure ) and plasmonic (gold nanorods, AuNRs, labelled as Au-1 and Au-2, depending on the size of the plasmonic core, see Figure and Figure ) components. We used TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxyl) oxidized cellulose nanofibers (CNFs) as a scaffold to preserve the intrinsic properties of both functional units and ensure their compatibility and co- functionality in water. In the first step, we prepared pre-composite material by relying on electrostatic attraction between AuNRs and CNFs. Nanoparticles, stabilized by a positively charged bilayer of surfactant (cetyltrimethylammonium bromide, CTAB, containing -𝑁(𝐶𝐻 3 ) 3 + head group, Figure stage I), were uniformly immobilized on a cellulose scaffold rich in carboxyl groups, -𝐶𝑂𝑂 -(Figure stage II). The adsorption of CTAB (as micelles or AuNRs bilayer) on cellulose lowered the hydrophilicity of the fibers and resulted in the sedimentation of the Au-decorated CNFs. We obtained the pre-composite as a phase-separated system (Figure , top) convenient for further processing via centrifugation.