This paper, "Economic Diversification beyond oil sector: A case of Azerbaijan," critically examines Azerbaijan's historical and ongoing "heavy dependence on its rich oil and gas fields" since 1991, which has led to economic vulnerability and "Dutch disease symptoms" due to "unexpected fluctuations in oil and gas prices" from 2014. It investigates whether Azerbaijan has achieved its proposed diversification goals, identifies decisive non-oil sectors, assesses existing economic attainments, and explores the main barriers. The underlying argument is that despite strategic efforts, including the "Strategic Road Map introduced in 2016" and subsequent "new strategy plans after 2021", the economy remains "largely oil-dependent" and faces significant structural challenges. Employing an analysis of statistical facts, information from other articles, and the "Economic Diversification Index" components (PCA output, revenue, and trade), the study reveals "low overall diversification", with domestic production (PCA Output 99.41), fiscal revenue (PCA Revenue 83.04), and export diversification (PCA Trade 74.25) highly concentrated in the hydrocarbon sector.