The alleged moves include striking a deal with Facebook to manipulate online advertising auctions, the states said.
This is the latest legal complaint facing the tech giant, which is under pressure from regulators globally.
Google rejected the claims, saying it would be "strongly" defending itself in court.
"We've invested in state-of-the-art ad tech services that help businesses and benefit consumers. Digital ad prices have fallen over the last decade. Ad tech fees are falling too. Google's ad tech fees are lower than the industry average," a company spokesperson said in response to Wednesday's lawsuit.
"These are the hallmarks of a highly competitive industry."
Facebook declined to comment.
The lawsuit takes aim at Google's control of the online advertising market, which it says was cemented in 2008 with its purchase of DoubleClick, the main software that publishers use to sell online advertising.
Google's advertising sales account for over 80% of its revenues.
The 10 states suing Google are Texas, Arkansas, Indiana, Kentucky, Missouri, Mississippi, South Dakota, North Dakota, Utah and Idaho, all of which have Republican prosecutors.
The states claim Google used its new role to benefit other parts of its business, for example by forcing publishers to license its advertising servers. The lawsuit also says the firm took steps to secretly undercut innovations that were circumventing its fees.
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