Through her production company Pacific Standard, the 38-year-old star served as a producer on the critically acclaimed thriller Gone Girl, and produced – as well as starred in – the adventure biopic Wild.
ET caught up with Witherspoon on the red carpet at the Beverly Hills premiere of Wild, where she opened up about how far her small production company has come since she founded it in 2012.
"I'm just so excited," Witherspoon said, smiling. "I didn't know what my production company was going to be when I started it a couple of years ago. And just to see it take off like this, you know?"
However, it was Witherspoon's brilliant choices of which novels to purchase the rights to and to adapt that have played a big hand in her production company's success.
"I just read a lot of books," a humble Witherspoon told ET. "And I picked these two books… it's been phenomenal to see how audiences have responded, and I'm so pleased."
Wild is based on the memoir by Cheryl Strayed and chronicles her solo hike along thousands of miles of the Pacific Crest Trail in an attempt to find happiness after her life is turned upside down.
Check out the video for more from Witherspoon, and her Wild co-star Laura Dern.
Wild hikes into theaters December 5.
You can follow Zach Seemayer on Twitter @ZachSeemayer.