An electrochemically induced sol–gel process has been used to efficiently immobilize Ru(bpy)₃²⁺ in a 3D porous silica film matrix deposited on a glassy carbon electrode (GCE), forming a solid state electro-chemiluminescence (ECL) sensor. In this approach, electrolysis of the GCE at cathodic voltages from a solution of ammonium fluorosilicate containing Ru(bpy)₃²⁺ results in the reduction of water to hydroxyl ions and hydrogen bubbles. The former product catalyzes the hydrolysis of ammonium fluorosilicate to form a silica film; while the hydrogen bubbles act as a dynamic template in forming a porous silica matrix. Therefore, a large quantity of Ru(bpy)₃²⁺ ions can be efficiently encapsulated in the porous silica matrix, and the formed porous structure offers a good mass transport path. The fabricated [Ru(bpy)₃]²⁺ solid-state ECL sensor shows high sensitivity and stability towards the determination of tripropylamine (TPA). The electrochemically generated luminescence signal shows a good linear relationship to TPA concentration ranging from 3.46 × 10⁻¹⁰ to 3.70 × 10⁻⁶ M and 3.70 × 10⁻⁶ to 3.60 × 10⁻⁴ M, with an extremely low detection limit of 17 pM (S/N = 3). The present approach is effective for encapsulation of various molecules and could find wide application in the construction of various sensors.