Gold nanoparticles are platforms that can be immobilized with probe, so they can be used as biosensors. In health sector, biosensors are used for biomedical applications, such as for DNA marking and cell isolation. In addition, it can be used as a method for Halal Authenticaton applications for meat products. This study aims to determine the optimum conditions for the synthesis of gold nanoparticles as platform for immobilization and application of AuNPs-MB as biosensors with the colorimetry method for Halal Authentication applications for meat product. This research was optimize synthesis of gold nanoparticles using 6 series of HAuCl4 concentration, there are 0.0635; 0.127; 0.19; 0.254; 0.635; dan 1.27 (mM). The most optimum concentration, then immobilized with probe MB and measured using Uv-Vis Spectrophotometer to see the absorption and using Scanning Electron Microscope (SEM) to see the size and distribution of nanoparticles. The results showed that 0.19 mM of AuNPs, gave the best results, which was stable for 3.5 months, has good results by measured using SEM with an average size of 21.7 nm. The value absorbance before to after immobilization was decreased, from 0.226 to 0.167 and indicate that the proses is success. The conclusion of this study is AuNPs-MB is proven to be a biosensor for Halal Authentication applications using colorimetric method.