BEIJING—Chinese ride-sharing platform Didi Chuxing Technology Co. raised $4 billion in fresh funding, pushing its valuation closer to rival Uber Technologies Inc. and giving it ample money to spend on self-driving vehicles and other artificial-intelligence systems.

Investors in Didi’s new funding include Japanese mega-fund-manager SoftBank Group Corp. and Mubadala Investment Co., an Abu Dhabi state fund, people familiar with the matter said Thursday. The company announced the funding without naming the investors.

The...