According to CNBC, multi-billion dollar payments start-up Stripe just got a new cash injection and a bit more valuable.

The company said this week that it raised an additional $100 million from Tiger Global Management, boosting its valuation to $22.5 billion. This round, first reported by the Information, follows a $245 million Series E fundraise announced last fall that put its valuation at $20 billion.

Stripe has become one of the most sought after payment start-ups in Silicon Valley. It's now one of the most valuable "unicorns" -- private firms worth more than $1 billion -- in the U.S., beating data analytics firm Palantir's $20 billion water mark. It's by far the most valuable private fintech company, with cryptocurrency exchange Coinbase trailing behind at an $8 billion valuation, according to CB Insights.

Stripe's online platform integrates electronic payments and secure transactions, and has become an attractive bet for venture capital as consumers overwhelmingly move to online payments.

In addition to Tiger Global, the San Francisco-based start-up has also attracted investments from Andreessen Horowitz, Peter Thiel, Elon Musk, Google's venture arm Capital G, Sequoia Capital and Kleiner Perkins, among others, according to Pitchbook.

"Stripe is rapidly scaling internationally, as well as extending our platform into issuing, global fraud prevention, and physical stores with Stripe Terminal," a Stripe spokesperson said in an emailed statement. "The follow-on funding gives us more leverage in these strategic areas."

Stripe, whose rivals including Jack Dorsey's Square and Netherlands-based Adyen, makes software that allows businesses to accept payments over the internet. The start-up was founded in 2010 by Irish brothers Patrick and John Collison, who came up with the idea for Stripe while attending MIT. CEO Patrick Collison announced on Twitter this week that former Google Cloud CEO Diane Greene was being added to the board.

"We're building Stripe for the long-term," Collison said on Twitter. "We're lucky to do so alongside a roster of detail-oriented directors who think that infrastructure revolutions can compound for decades and that operational excellence can be a surprisingly durable competitive advantage."

Fintech has been luring in huge investment worldwide. According to CB Insights, the sector raked in close to $40 billion in venture capital backing last year. Tiger Global has become an increasingly active investment player in the tech space. Last year, the firm raised $3.75 billion for a new venture capital fund focused on consumer internet, cloud and industry-specific software globally.

The firm has invested in a host of tech companies recently, including Coinbase, Indian ride-hailing firm Ola and American restaurant delivery service Postmates.