The firm also helps to co-ordinate refills and renewals.
Pharmacy shareholders will perhaps find solace in the fact that they're not the only industry to have billions in market value erased by a single Amazon announcement.
"We want to help them continue making it easy for people to save time, simplify their lives, and feel healthier".
TJ Parker, PillPack's co-founder and chief executive, said: "Together with Amazon, we are eager to continue working with partners across the healthcare industry to help people throughout the United States who can benefit from a better pharmacy experience".
FILE PHOTO: The Walgreens logo is seen outside the store in Times Square in NY, U.S., July 5, 2016.
With its user-friendly packaging and design, PillPack has shaken up the pharmacy business, generating more than $100 million in revenue a year ago.
Korea end Russian Federation 2018 with stunning win, 2 painful losses
Sweden, with their greater physicality, were on top, but Mexico were unsafe on the break. Even in Yekaterinburg, almost 500 miles away, the Mexican fans expected Germany to score.
At the time, Parker argued that the company was working to protect its monopoly on home-delivered prescriptions, which Express Scripts disputed. The deal is expected to close in the second half of 2018, according to a statement from the companies.
"Amazon's acquisition of PillPack is a warning shot in what is about to become a major battle within the pharmacy space", said Neil Saunders, managing director of GlobalData Retail.
He added this "is only the first play" in an increasingly aggressive strategy by Amazon for a much more significant role in pharmacy.
'Pharmacy networks are controlled by managed care companies and pharmacy benefit managers with captive mail order capabilities. Walmart was reportedly interested in buying PillPack earlier his year, but Amazon seems to have won out in the end.