Asprey developed his Bulletproof Coffee recipe after traveling to Tibet and tasting yak-butter tea drinks. He returned to the United States and experimented with buttered drink recipes and published the preparation for his buttered coffee drink on his blog in 2009. The Bulletproof diet also recommends incorporating intermittent fasting.

Asprey initially started the Bulletproof brand after developing Bulletproof Coffee. He posted the recipe for the beverage and details on the health benefits he experienced on his website while still working for Trend Micro. Asprey also developed “low-mold coffee beans”, oils, and supplements and started selling them on his website in 2011. The following year, Asprey was a panelist at the “Hack Your Brain” event at South by Southwest. By 2013, Asprey had left his position at Trend Micro to run the Bulletproof companies.

Asprey founded Bulletproof 360, Inc. in 2013 and founded Bulletproof Nutrition Inc. in 2014.

In 2014, Asprey authored The Bulletproof Diet published by Rodale Books.

On July 25, 2015, Asprey opened a cafe in Santa Monica selling Bulletproof Coffee and high fat foods.

In July 2015, Asprey raised $9 million from Trinity Ventures to expand the company.

In June 2017, Asprey partnered with Ross Franklin, CEO and Founder of Pure Green, to launch Bulletproof Coffee in New York City.