The deal, the value of which was not disclosed, was announced in a post on The Find's website.
"Key members of our team are joining the company and will be working hard to integrate our technology to make the ads you see on Facebook every day better and more relevant to you," the company said.
That probably means the ads Facebook users see will be more relevant to products they've been browsing and buying online, perhaps highlighting local retailers. One of The Find's features is that it attempts to mix online and local stores and says its results are based on "your social profile."
The company says its shopping index contains more than 500 million [m] products from 500,000 stores.
For Facebook, the technology might make the social network a more valuable platform for merchants.
The Find's own website won't survive the acquisition.
"Unfortunately, this means we will be taking our search engine offline in the next few weeks," it said.
Martyn Williams covers mobile telecoms, Silicon Valley and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is email@example.com