While making an appearance on The Ellen DeGeneres Show, the House of Lies actress showed a video in which she broke down into hysterical tears over the thoughtful gift.
Bell has since confessed that she was too excited by the gift.
"[Fiancé] Dax [Shepard] brought a sloth to me for a few hours as a birthday present," Bell explained to New York Magazine. "I've always loved sloths.
"It was one of the best days of my life almost to the point where I couldn't handle it - it was that exciting. I lost my mind."
The actress later confessed that while it was difficult to share such a personal video, she was happy to have made her fans laugh.
House of Lies airs Sundays at 10/9c on Showtime.
Watch Kristen Bell receive a sloth for her birthday below: