Nanoparticles are progressively being incorporated into the printing industry and research is underway to enhance their use to boost innovation and competitiveness. Precursors or metallic nanoparticles replace ink pigments in printed electronics, imparting electrical conductivity to the resulting printed patterns. Many types of conductive inks have diverse characteristics that are best suited to specific applications and have different preparation techniques. Conductive inks are a pertinent element of the broader functional printing area, which is currently expanding and is seen as one of the most pertinent future technologies in the printing industry. In this review, the aspects of selecting, functionalizing, and making nanomaterials based conductive inks for printable, flexible and wearable electronics. Various methods and mechanisms for developing conductive inks based on nanomaterials, such as Ag nanoparticles, Cu@Ag core-shell nanoparticles, graphene conductive ink, biocompatible CNT ink, conductive indium tin oxide (ITO), proposed by various research groups are summarized. We have also attempted to provide insights into enhancing printing ink parameters such as uniformity, flexibility, resolution, and durability which are considered to be very important aspects for any printable inks. Finally, the applications of the conductive ink in thin film transistors (TFT), dye sensitized solar cells (DSSC), Radio Frequency Identification (RFID) tags, and sensors are summarized.