Amazon plans to build major new campuses in New York City and next to the Pentagon near Washington DC, and expand its operations in Nashville.
The decision comes 14 months after the tech giant kicked off a continent-wide competition by announcing a search for a "second headquarters" location.
The contest drew 238 bids, as local officials leapt at the chance to land a potentially transformative investment.
The three locations could create some 55,000 jobs in the next two decades.
Amazon said it expected to invest about $2.5bn each in New York and Arlington, where the offices are planned to host more than 25,000 "high-paying jobs".
It said Nashville, Tennessee would become Amazon's new East Coast hub of operations, creating another 5,000 positions.
In exchange, the e-commerce giant is due to receive more than $2bn (£1.9bn) worth in tax benefits and other incentives from the state and local governments.
Amazon had originally said it was looking to build a single "HQ2" in a large urban area, with proximity to a major airport and access to mass transit.
The company said at the time that the new premises would create as many as 50,000 jobs and cost at least $5bn to build and operate.
However, Amazon eventually decided to split the jobs and investment between two different locations.
On Tuesday, the firm said the division would allow it to "attract more top talent", especially in software development, when hiring starts in 2019.