The fine is thought to constitute the single largest settlement made in a privacy case to the FTC, which polices anti-competitive or other business practices that may be unfair to the consumer.
It would also mark the second time that Google has been hit by a fine by US authorities.
Google's Doubleclick ad network was able to work around cookie settings in the Safari browser, which is the default for both the iPhone and iPad, but also used on other Apple products and PCs, and has a market share estimated to be between 5% and 8%.
Apple's Safari browser blocks ads served by networks such as Google's Doubleclick. Google was found to have worked around the block, and serve ads regardless.
Google has never admitted liability for the workaround, which it claims was unintentional.
A Google spokesman said: "We cannot comment on any specifics. However, we do 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 would not comment on the case, but an announcement is expected shortly.
This is not the first time Google has fallen foul of the FTC, and was fined $25,000 for capturing Wi-Fi data in April. Google is also subject to an FTC review, to explore whether the company is overly dominant in search.
Facebook settled its own privacy issues with the FTC in November last year.