This study develops a facile approach to fabricate adhesives consists of epoxy and cost-effective graphene platelets (GnPs). Morphology, mechanical properties, electrical and thermal conductivity, and adhesive toughness of epoxy/GnP nanocomposite were investigated. Significant improvements in mechanical properties of epoxy/GnP nanocomposites were achieved at low GnP loading of merely 0.5 vol%; for example, Young’s modulus, fracture toughness (K1C) and energy release rate (G1C) increased by 71%, 133% and 190%, respectively compared to neat epoxy. Percolation threshold of electrical conductivity is recorded at 0.58 vol% and thermal conductivity of 2.13 W m−1 K−1 at 6 vol% showing 4 folds enhancements. The lap shear strength of epoxy/GnP nanocomposite adhesive improved from 10.7 MPa for neat epoxy to 13.57 MPa at 0.375 vol% GnPs. The concluded results are superior to other composites or adhesives at similar fractions of fillers such as single-walled carbon nanotubes, multi-walled carbon nanotubes or graphene oxide. The study promises that GnPs are ideal candidate to achieve multifunctional epoxy adhesives.