Grab, like Uber and Didi, is a car booking service provider through its mobile phone application. The company is well-known in Southeast Asia and has 75,000 registered members across the region.
The service is available in Singapore, Malaysia, Philippines, Vietnam and Indonesia.
Uber is the company's main competitor. Grab has been trying to get a bigger chunk of the markets in Indonesia and Malaysia through forming of partnerships with Blue Bird and MyTeksi.
However, Grab's financial portfolio in Singapore is not looking good. Grab Singapore declared a net loss of $39.8 million last year.
The influx of Didi's investment is seen to help the company to revive from the loss.
In China, Didi, with its new wave of funding, is on the move to build mergers with other car-hailing services across the globe. They are now negotiating with Ola in India and Lyft in the U.S.
Adrian Li, managing partner at Convergence Ventures, said, "Didi probably has a lot of reserves from what they thought might be a longer war in China."
He added, "Now they will be able to put the reserves in new growth markets like Southeast Asia and back a player they believe has a strong chance."
Grab is optimistic that Didi will be able to help them forge ahead in China, and would eventually translate to overall success in Southeast Asia.
Following the Uber-Didi merger, Grab co-founder Anthony Tan, sent a motivational letter to its employees.
The letter stated, "With the deal in China, we expect Uber to turn more attention and divert resources to our region. But we have seen that when the local champion stays true to their beliefs and strengths, they can prevail. We see this happening in China, and it will be the same here. They've lost once, and we will make them lose again."