The tech giant may be forced to allow rival application marketplaces within the United Kingdom.
The iPhone maker could be required to allow competitors to run separate app stores on iPhones in the UK, following a ruling from the competition regulator.
This would be a major shift to the company's well-known "closed system" where apps can only be installed from its own official marketplace.
But the Competition and Markets Authority has designated both the tech giants as having "strategic market status" - effectively saying they have significant control over mobile platforms.
Watchdog Findings
The CMA said the two companies "may be limiting progress and market rivalry".
But the regulator emphasized it did not "find or assume misconduct" from the companies.
"Mobile applications generates 1.5% of the UK's GDP and supports around four hundred thousand positions, which is why it's crucial these sectors function properly for enterprises," commented a senior official from the competition authority.
Approximately ninety to one hundred percent of British smartphones run on Apple or Google's operating systems, creating what the regulator calls an "virtual monopoly".
According to recent analysis, 48.5% of UK mobile owners use an iPhone - which runs the iOS operating system - with the overwhelming bulk of the rest using the Android OS.
Apple's Response
The CMA's investigation focused on how prominent the companies' own applications are compared with rivals - as well as their browsers and platform software.
It is unknown what modifications the authority will seek to implement, but earlier it published guidelines detailing potential measures it could take.
These comprise requiring it to be easier for people to transition between iOS and Android devices, and for both firms to list applications "in a fair, objective and transparent manner" in their marketplaces.
Apple specifically may be compelled to permit third-party marketplaces on its devices, and let people to download programs directly from companies' websites.
This would follow comparable regulations in the European Union, which previously imposed measures against Apple for restrictive practices.
The technology firm warned the UK could face delays to receiving updates - as has occurred in the European Union - which the company attributes to strict rules.
For instance, some Apple Intelligence features which have been launched in other parts of the world are not accessible in the European market.
"We encounters fierce competition in every market where we operate, and we strive continuously to create the finest offerings, services and user experience," the organization said in a statement.
"Britain's implementation of European regulations would weaken that, leaving users with weaker privacy and security, delayed access to new features, and a divided, more complicated user journey."
Google's Standpoint
Google device owners can currently use alternative marketplaces - though critics say they are not as user-friendly as Google's own application marketplace.
The regulator's plan said the search company may have to "modify the interface" of downloading apps directly from online sources, as well as "remove user frictions" when using third-party platforms.
"There appears to be no the rationale for today's designation decision," a company policy executive remarked.
The executive said "most" of Google device owners use alternative app stores or install applications straight from a developer's website, and claimed there is a much wider selection of apps offered for Google device owners versus those on Apple devices.
"There are now twenty-four thousand Android phone models from 1,300 phone manufacturers globally, facing strong rivalry from iOS in the UK," the spokesperson continued.
Android is an open-source operating system, which means developers can use and build on top of it for free.
The company argues this means it promotes market competition.
But advocacy organizations said curbs on these companies' power in different nations "are already helping businesses to innovate and providing customers more choice".
"Their dominance is now creating genuine problems by restricting choice for consumers and market rivalry for businesses," stated a policy expert.