The 37-year-old actor will emcee the 24th edition of the annual awards on January 21 next year.
In a statement posted on the awards official website, Executive Producer Kathy Connell said, "We are delighted to have Kristen Bell as the first-ever host of the SAG Awards."
"This has been a year in which assumptions have been challenged, stereotypes have been shattered, and precedents have been broken. We decided to capture the cultural mood by casting aside one of our own traditions, and we're thrilled to have such a talented performer like Bell help us do so," she added.
"I am honoured to be part of the SAG Awards, and am a little nervous about being its first-ever host," Bell said.
"I'm so glad that I'll be in the company of my fellow actors, many of whom I've worked with before, so I know theyll be warm and supportive. It's going to be an amazing night," she added.