Internet of Things-enabled smart grid (SG) technology provides ample advantages to traditional power grids. In an SG system, the smart meter (SM) is the critical component that collects the power usage information related to users and delivers the accumulated vital information to the central service provider (CSP) via the Internet, imperiled to numerous pernicious security threats. Consequently, it is crucial to preserve the integrity of the communication between SMs and CSP for the smooth running of the SG system. Authentication protocol effectively enables SM and CSP to communicate securely by establishing a secure channel. This paper presents an anonymous and reliable authentication protocol for SG (ARAP-SG) to enable secure and reliable information exchange. The proposed ARAP-SG uses the hash function, elliptic curve cryptography, and symmetric encryption to complete the authentication phase. ARAP-SG guarantees reliable information exchange during the authentication phase while conserving the anonymity of both SP and SM. Additionally, ARAP-SG authorizes CSP and SM to construct a session key (SK) after accomplishing the authentication phase for undecipherable information exchange in the future. We utilized the random oracle model to corroborate the security of constructed SK. Moreover, we demonstrate that ARAP-SG is proficient in thwarting covert security attacks by effectuating informal security analysis. Furthermore, Scyther-based corroboration manifests that ARAP-SG is secure. Finally, we explain through a comparative analysis with relevant authentication protocols that ARAP-SG entails 25.5-56.76% and 7.69-49.47% low computational and communication overheads, respectively, with improved security properties.