39-year-old Williams announced the big move on Tuesday ... saying she's pumped to put new and inspiring stories onto the screen -- including her own, via a new docuseries following her life on and off the court.

"I’m very excited to be partnering with Amazon Studios – they are developing some of the most inspiring and important content for a global audience," Williams said.

The deal includes scripted and unscripted content ... which will all be made available via Amazon.

"I have a lot of stories I’m eager to tell, including a continuation of my own, and I look forward to sharing those with the world."

Williams' docuseries -- title TBD -- will be produced by Plum Pictures, Goalhanger Films and Amazon Studios. Williams will also serve as executive producer on the project.

Of course, Williams is one of the best tennis players EVER -- she's won 23 Grand Slams, 73 championships and has won nearly $95 million in prize money throughout her career.

So yeah, Amazon is stoked to have her on board.

As Head of Amazon Studios Jennifer Salke put it ... "Serena has transformed her sport and become one of the most inspiring athletes, entrepreneurs and women of her generation, admired not only for her unmatched prowess on the court but for her dedication to advocacy as well."