Polyaniline (PANI) has been widely used for the energy storage applications either as a conducting agent or directly as an electroactive material due to the tunable pseudocapacitive performance owing to its various oxidation states. Although PANI supercapacitors are known for over three decades, immediate attention has been paid just over the past few years due to the potential practical applications. Here, we extensively review recent works on PANI-based supercapacitors using nanocomposites of PANI with other electrochemically active materials including carbonaceous materials and metal oxides. Recent works on developing new electrolytes for PANI supercapacitors including utilization of additional redox systems within the electrolyte, neutral electrolytes, and solid-state electrolytes are discussed. Some other interesting applications of PANI in energy-related applications are also covered in this review.