As well as the penalty, the order also requires Google to disable all the tracking cookies it had said it would not place on consumers' computers.
It emerged in February that Google had circumnavigated Apple's Safari browser privacy-protection measures, to drop cookies that enabled it to serve targeted advertising.
The FTC found that for several months in 2011 and 2012, Google placed an advertising tracking cookie on the computers of Safari users who visited sites within Google’s DoubleClick ad network, even though it has previously told these users they would automatically be opted out of such tracking, because of default settings in the Safari browser in Macs, iPhones and iPads.
The FTC alleged that Google told Safari users they did not need to worry about the unavailability of opt-out, because Safari's cookie controls would provide the same protection as the opt-out.
According to the FTC, this promise was not kept and Google ended up placing tracking cookies in many Safari users' browsers, despite its promise to give those users the same treatment as opted-out users.
The FTC charged that Google's misrepresentations violated a previous settlement reached in October last year, which barred Google from misrepresenting the extent to which consumers can exercise control over the collection of their information, resolving privacy charges relating to the launch of its social network, Google Buzz.
Jon Leibowitz, chairman of the FTC said the record penalty sent a "clear message to all companies under an FTC privacy order".
He said: "No matter how big or small, all companies must abide by FTC orders against them and keep their privacy promises to consumers, or they will end up paying many times what it would have cost to comply in the first place."
Google gave a robust defence in a statement saying: "We set the highest standards of privacy and security for our users. The FTC is focused on a 2009 help center page published more than two years before our consent decree, and a year before Apple changed its cookie-handling policy.
"We have now changed that page and taken steps to remove the ad cookies, which collected no personal information, from Apple's browsers."
The FTC wrote on its blog yesterday (9 August): "To its credit, Google started destroying those cookies early, without waiting for the settlement to be finalised, so virtually all of the relevant cookies should be gone by now."
This is the second time Google has been fined by the FTC this year, after receiving a $25,000 (£15,900) penalty in April for capturing personal data from Wi-Fi networks, via its Street View cars.
Google is also subject to an ongoing FTC probe, to explore whether the company is overly dominant in search.
In Europe, the EU's investigation into Google appears to be close to resolution, with reports saying a settlement is in the process of being drawn up.Follow @shearmans