The highest point in the company's history was when Facebook acquired it for $22 Billion. While Acton didn't mention when exactly he will be stepping off, sources tell VentureBeat the action will take place sometime this year in November.
Acton's move came to fore after he posted on Facebook about his decision.
Facebook bought WhatsApp in 2014 for $19 billion in cash and stock.
Making the announcement to colleagues at a WhatsApp meeting at Facebook headquarters on Tuesday, Acton later posted the news to his Facebook page.
In the same Facebook post, Brian also added that he was fortunate that all good things happened early in his life so that he could take more risks and start a new venture at such a young age. He said he intends to start a foundation "focused at the intersection of nonprofit, technology and communications". "I'll have more to share in the coming months".
After the acquisition by Facebook, Acton was leading the engineering efforts at WhatsApp. He also declares that the decision to leave WhatsApp was "a tough one", as he is proud of his team and what they've managed to accomplish in "only a few years". According to Forbes, Acton has a net worth of $6.5 million.
Twitter too denied him a job and he went on to co-found WhatsApp, a free cross-platform instant messaging service for smartphones.
WhatsApp recently confirmed that it's working on a dedicated enterprise app through which businesses will be directly able to contact their users.