Kenneth Lin, founder and CEO of Credit Karma, on stage during day two of MoneyConf 2018.

Credit Karma, one of the world's most valuable financial technology (fintech) companies, is buying U.K. credit scoring service Noddle from TransUnion to make its first expansion beyond North America.

The deal, announced Monday, will see Noddle's more than 35 employees in the English cities of London and Leeds join Credit Karma. The San Francisco-based company, which currently operates in the U.S and Canada, plans to more than double its British workforce in the next 12 months.

The agreement will also see Credit Karma add Noddle's more than 4 million customers to its platform, increasing the fintech firm's total global user base to over 89 million.

Financial terms of the transaction were not disclosed. The acquisition is subject to approval from U.K. financial watchdog the Financial Conduct Authority, and is expected to close either later this year or by early 2019.

Nichole Mustard, Credit Karma's chief revenue officer, said the personal finance firm chose Noddle as its acquisition target due to the service's status as an early mover in the free credit scoring space. The platform was launched in 2011 by its then-parent company Callcredit.

"I think when you're entering a new market, the ability to get scale is important," she told CNBC over the phone on Monday.

Mustard said the firm would look to "employ everything" it currently offers in the U.S. and Canada to British customers, and would seek to understand the U.K. market more as it enters the country. She added that she saw a "significant opportunity for growth" in Britain.

Credit Karma offers customers free access to credit scores and reports from credit reporting agencies Equifax and TransUnion. It makes money by matching users with financial products like credit cards and personal loans offered by lenders.

The firm says it is profitable and, according to a report by Bloomberg earlier this year, it posted revenue of $682 million last year — although that missed its own 2017 revenue goal of $790 million, the publication reported, citing an internal presentation.

Since it was founded in 2007, the company has evolved its services to help connect customers with other products, including auto loans and insurance.