Fitness tracker company Fitbit files to go public on the NYSE under the symbol 'FIT'.

Fitbit Inc., a pioneer in wearable fitness tracking, on Thursday filed for an initial public offering to help fend against a mounting assault from a range of corporate giants eager for a piece of the burgeoning market.

The San Francisco maker of devices that track movement and sleep quality revealed it earned a $131.8 million profit last year on revenue that nearly tripled to $745.4 million. Since 2007, Fitbit has sold roughly 20.5 million of its fitness-tracking devices—from the $60 Zip clip-on to the $250 Surge wristwatch—with more than half sold last year alone.

Fitbit said Thursday it is seeking to raise up to $100 million, although that amount is a placeholder and is subject to change. It aims to trade on the New York Stock Exchange under ticker symbol FIT. The company valued itself at roughly $1.2 billion in March. It isn’t yet clear what valuation the company will seek in the IPO.

Its products’ novel ability to count the number of daily steps and monitor distance traveled and calories burned seized the attention of data-obsessed modern consumers and paved the way for a new category of hardware technology.

Celebrities such as author David Sedaris and basketball player Shaquille O’Neal have professed their love for Fitbits, and President Barack Obama has been spotted wearing the Fitbit Surge in public outings.

But that success also has attracted a wealth of competitors, as Fitbit acknowledges in its IPO filing. Tech giants such as Apple Inc., Microsoft Corp. and Samsung Electronics Inc.all have launched smartwatches with the ability to monitor exercise, while Google Inc.’s Android platform has been embraced by a number of big hardware makers. Then there are smaller electronics makers such as Garmin Ltd., Jawbone and Misfit, as well as sporting-goods companies like Nike Inc. and Under Amour Inc., which all sell fitness bands on the market.

Fitbit also has had to recover from a big knock to its brand. In early 2014, the company was stung by a series of complaints from consumers that one the company’s fitness-tracking bracelets, the Fitbit Force, caused rashes on their wrists. Fitbit recalled the product in March 2014, saying a small percentage of its customers experienced an allergic reaction to materials in the bracelet.

In addition to the reputational hit, Fitbit’s IPO filing revealed that the recall cost the company $84.6 million in pretax income in 2013 and another $22.8 million last year. The recalls also led to lawsuits filed against the company. Fitbit says it has settled all class-action lawsuits, though a number of personal-injury claims remain unresolved.

Fitbit warned these claims could lead to “substantial” litigation or settlement costs.

Also, it is unclear how many Fitbit consumers remain loyal users. Of the 20.5 million devices sold since its launch, just 9.5 million were actively used in the first three months of the year, according to the IPO filing. Some earlier models may no longer be used because consumers upgraded to newer iterations.

The company, with 579 employees at the end of March, said its products are now sold in 45,000 retail stores in more than 50 countries, and commands 68% of the fitness-tracker market, according to NPD Group.

Fitbit’s 38-year-old chief executive, James Park, co-founded the company in 2007 with his business partner, Eric Friedman. Mr. Park, a Harvard dropout, came up with the idea after playing videogames at home, struck by the way the Nintendo Wii combined motion sensors and software. Messrs. Park and Friedman each own a 10.9% stake in Fitbit, according to the filing.

The company has raised at least $83 million in venture-capital funding from investors such as Foundry Group, True Ventures and SoftBank Capital. Foundry Group is the biggest shareholder with a 28.9% ownership.

Morgan Stanley, Bank of America Merrill Lynch and Deutsche Bank are listed among the underwriters of the IPO.