The Seattle Post-Intelligencer reported Saturday that the purchase does not cancel out Amazon's plans to build three new office buildings in the Westlake Avenue area.
Each of those buildings is expected to include 1 million square feet of space with a maximum height of each of 37 stories.
The price for the 11-building purchase -- which includes 1.8 million square feet of space -- is $644 per square feet, the Seattle Times reported.
The 11 buildings were developed by Vulcan Real Estate, which is owned by another Seattle success story, Paul Allen, a co-founder of Microsoft Corp.
"Seattle ought to feel really good about an employer of Amazon's magnitude making a commitment like this," said Vulcan vice president Ada Healey.
"We didn't expect this outcome. We did not know Amazon was going to be the buyer," Healey said.