AI is increasingly being used in drilling operations, redefining efficiency, cost-effectiveness, and safety within the oil and gas industry. Traditional drilling operations are usually plagued by inefficiencies, high NPT, and suboptimal well placement due to over-reliance on manual decisions and conventional geological interpretation. AI-driven automation uses machine learning, IoT devices, real-time data analytics, and predictive maintenance to provide improved drilling precision, better placement of wells, and reduced operational risks. Industry leaders have shown that the gains in efficiency are huge; Chevron recorded a 30% increase in drilling speed, with a corresponding 25% reduction in operational costs, resulting from AI-driven automated drilling. Shell reported 130% gains in drilling efficiency due to AI-enhanced optimization models. BP and ExxonMobil implemented AI predictive maintenance, realizing a 20% reduction in maintenance costs, with a resulting 15% increase in equipment uptime. Saudi Aramco optimized well placement, leading to a 35% increase in production and reduced drilling time. This review critically assesses such AI applications in drilling automation with regard to operational efficiency, cost reduction, and sustainability. While a game-changing technology, several barriers to widespread diffusion exist: integration of data, which is highly complex; costs of implementation, which are relatively high; and skilled people are required. The ability to remove these barriers through technological development and strategic collaboration by the industry will be key in maximizing the full benefits of AI in drilling automation.