Compositions and methods for producing chitin and chitosan are provided. The compositions comprise genetically modified organisms, including fungi, yeast, bacterial and plant organisms that have been engineered to express heterologous genes involved in chitin and chitosan synthesis. Microorganisms and plants that have been modified for production of chitin and/or chitosan within the vacuole of a cell are encompassed. Methods for production of chitin also comprise culturing the genetically engineered organisms in conditions that allow for chitin production. Further methods include converting the chitin to chitosan by a chemical process. Production of chitosan also comprises culturing organisms that are genetically modified to produce chitosan without the need for chemical modification. Methods for in vitro chitosan production are also encompassed.