The "Call Me Caitlyn" costume consists of a padded top, matching shorts and a wig, and is very reminiscent of the outfit Jenner wore on the cover of Vanity Fair.
Spirit Halloween and AnytimeCostumes.com are one of several retailers carrying the costume, which is selling for $74.99.
"Caitlyn Jenner has proven to be the most important real-life superhero of the year, and Spirit Halloween is proud to carry the costume that celebrates her," the company said in a statement. "At Spirit Halloween, we create a wide range of costumes that are often based on celebrities, public figures, heroes and superheroes. Caitlyn Jenner is all of the above and our Caitlyn-inspired costume reflects just that. The costume will be available at Spirit Halloween stores and online by the end of September."
Meanwhile, many people on social media are criticizing the costume.
A petition on www.change.org says, "Do not turn Caitlyn Jenner into a costume. Your profit will only lead to greater transphobia and marginalization of an already at risk community."