Electrochemiluminescence (ECL) technique is defined as luminescence emitted as a result from the occurrence of chemical reaction on the electrode’s surface between luminophore (the light-emitting chemical species) and other species present in the same system when a small potential is applied to the electrode. ECL technique is oftentimes adopted for devising biosensors for the detection of various kinds of proteins by manipulating the interactions between antibody (Ab) and antigen (Ag) - these biosensors are also known as immunosensors. This technique is advantageous for immunosensors as it offers numerous benefits including straightforward operation and low background signal. Furthermore, the performance of these immunosensors can be elevated by integrating carbon nanomaterials (CNMs) into the biosensors and exploiting their excellent electrocatalytic properties for improving the sensitivity and specificity of the biosensors. This chapter comprises of an overview of ECL-based immunosensors integrated with CNMs, accentuating their recent developments and applications.