Kristo Kaarmann, Co-Founder & CEO, TransferWise, on Centre Stage during day one of MoneyConf 2018 at the RDS Arena in Dublin. (Photo By Eóin Noonan/Sportsfile via Getty Images)

TransferWise, one of Europe's largest financial technology (fintech) start-ups, said Monday it was profitable for the second year in a row.

The London-headquartered money transfer firm reported an annual post-tax net profit of £6.2 million ($8 million) for the fiscal year ending March 2018.

Annual revenue nearly doubled to £117 million during the period, from £66 million the previous year, TransferWise said. Operating profit came in at £9.5 million following a loss of £519,000 last year.

The company's accounts entered into the black for the first time in March 2017, six years after the firm was founded by Estonian entrepreneurs Taavet Hinrikus and Kristo Kaarmann.

"We've proven that fintech can offer consumers an unbelievable experience at a low price, all whilst creating a solid business that can be trusted long-term," Kaarmann, TransferWise's chief executive, said in a statement Monday.

"Looking forward, sustained growth and our healthy financial position means we can continue to drive down costs whilst investing in developing our product."

TransferWise is counted among Europe's "unicorn" start-ups — firms valued at $1 billion or more — with a reported valuation of $1.6 billion.

It has raised a total of $397 million since it was founded in 2011. Backers include asset management giant Old Mutual, Silicon Valley venture capital firms Institutional Venture Partners and Andreessen Horowitz, and British billionaire Richard Branson.