Facebook Inc. has signed up more than a dozen companies including Visa Inc., Mastercard Inc., PayPal Holdings Inc. and Uber Technologies Inc. to back a new cryptocurrency it plans to unveil next week and launch next year.

The financial and e-commerce companies, venture capitalists and telecommunications firms will invest around $10 million each in a consortium that will govern the digital coin, called Libra, according to people familiar with the matter. The money would be used to fund the creation of the coin, which will...