Apple pomace is the processing waste generated after apple juice manufacturing and represents up to 30% of the original fruit. This solid residue consists of a complex mixture of peel, core, seed, calyx, stem, and soft tissue. This residual material is a poor animal feed supplement because of its extremely low protein content and high amount of sugar. The application of agroindustrial by-products in bioprocesses offers a wide range of alternative substrates, thus helping solve pollution problems related to their disposal. Attempts have been made to use apple pomace to generate several value-added products, such as enzymes, single cell protein, aroma compounds, ethanol, organic acids, polysaccharides, and mushrooms. This article reviews recent developments regarding processes and products that employed apple pomace as a substrate for biotechnological applications.