In this paper, a new multifunctional electrochemical platform for hydrogen peroxide (H2O2) and nitrite (NO2) based on silver/carbon nano-composite (Ag/C NC) was firstly proposed. Ag/C NC was synthesized by using carbon dots (C-dots) as the reductant by a facile one-step synthesis method and confirmed by UV-Vis, Fourier transforms infrared spectroscopy, transmission electron microscopy, scanning electron microscopy and dynamic light scattering. The Ag/C NC based electrodes showed excellent electrocatalytic activity toward the reduction of H2O2 and the oxidation of NO2. When Ag/C NC was dropped on the bare GCE, the electrocatalytic reduction of H2O2 occurred and showed wide linear range from 5.00 mu M to 11.05 mu M with the detection limit of 0.51 mu M. When Ag/C NC was dropped on graphene (GR) modified electrode, the Ag/C NC/GR/GCE showed extremely fast direct electron transfer and good electrocatalytic activity toward oxidation of nitrite. It showed wide linear range from 4.00 mu M to 2.00 mu M with the detection limit of 0.48 mu M. The Ag/C NC/GR/GCE was successfully applied in analysis of nitrite in real samples and gained good testing recovery. Therefore, the proposed electrochemical sensors for H2O2 and NO2 exhibited many advantages, such as operational simplicity, rapid responses, good reproducibility and stability, and can be simply tuned to utilize for electrochemical detection of H2O2 and NO2. This study will open a facial and simple synthesis method for preparing carbon based noble metal nanocomposite and utilizes them in detection for different purposes, which may provide new opportunity and prospect in the field of electrochemical biosensing. (C) 2016 Elsevier Ltd. All rights reserved.