A series of new mononuclear multifunctional lanthanide(III)‐Schiff base complexes have been synthesized and characterized by elemental analyses, FTIR, 1H NMR and UV/Vis spectroscopy. Potentially tridentate, the Schiff‐base ligand is based on a ‘salicyldimine’ core with a long and flexible alkoxy group which coordinates to lanthanide ions in its zwitterionic form via the phenolic‐oxygen with the proton shifted to the imine‐nitrogen. The chelate nitrato groups complete a nine‐coordinate geometry. The ligand is non‐mesomorphic, while coordination to Ln3+ ion induces a liquid crystalline behavior. The complexes exhibited a thermally stable highly viscous partially bilayer smectic Ad phase in the 45‐135°C temperature range. The molecular organization of the complexes in the mesophase is conjectured to be based on a cylindrical‐like dimeric structure with the three alkoxy group pointing up and three pointing down assembling laterally into a lamellae. The Schiff base ligand is a blue light emitter exhibiting a broad emission maximum at 435 nm while the lanthanide complexes show an intense green emission. The Tb3+ complex, interestingly, also showed mesophase luminescence. The ligand and its complexes of La3+, Dy3+ and Yb3+ exhibited a significant second order non‐linear optical (NLO) activity representing the first example of lanthanidomesogens to exhibit such behaviour.