The class-action lawsuit was filed Wednesday in Changwon, South Korea, seeking 27 billion won, or roughly $26 million in damages.
It listed 26,291 plaintiffs, 921 of them minors whose parents must consent to their joining the litigation.
"We... electronically filed a suit seeking compensation from Apple and its South Korean unit for emotional damage caused by illegal location tracking by Apple's iPhone," the law firm added in a statement.
The problem was revealed when security researchers discovered a hidden file on the devices containing a record of everywhere they had been. The data allegedly included users' location information including longitude, latitude, and time stamps. With certain software, an iPhone user's movements can be mapped using the file.
Each claimant is seeking 1 million won ($932) in damages, said Kim Hyeong-seok, one of their attorneys.
Kim uses the iPhone himself, and after reviewing the legality of the matter based on Korean law, he concluded it was clearly illegal.
Kim was awarded 1 million won in June over iPhone privacy and has since led online preparations for a class action suit against Apple and its South Korean unit. This issue has been fixed by Apple after the company released a software update that resolves the problem.
"The suit accuses Apple of breaching articles 10 and 17 of the constitution that ensure pursuit of happiness and protection of privacy, and the South Korean law on protection of location data," a spokesman for Kim's firm Miraelaw told AFP.
Apple has faced criticism after it revealed in April that its iPhones were storing locations of nearby cellphone towers and Wi-Fi hotspots for up to a year. The tech giant also revealed that a software bug caused iPhones to continue to send anonymous location data to the company's servers even when location services on the device were turned off.
Legal challenges for Apple have then flooded the technology giant. Its Florida lawsuit over the tracking has not met a conclusion yet.
The Korea Communications Commission said in early August that it would order Apple to pay a 3 million won fine for violating the country's location information laws.
Before a judgment is made in this latest case in Korea, more plaintiffs may confront Apple, commented the Associated Press.
More people are allowed to join the lawsuit until the end of this month.
The first hearing in the case to take place in October or November, according to Kim.