The yellow-faced puppet Julia will debut on screen in April, having appeared in printed form in some Sesame Street storybooks.
The character has been designed to embody some of the traits and behaviours that autistic children might display, including overactive excitement and difficulties in conversation.
Julia will be puppeteered by Stacey Gordon, the mother of an autistic son.
"Had my son's friends been exposed to his behaviours through something that they had seen on TV before they experienced them in the classroom, they might not have been frightened," she said on CBS News.
"They might not have been worried when he cried. They would have known that he plays in a different way, and that that's OK."
Show writer Christine Ferraro told CBS News: "The big discussion right at the start was, 'How do we do this? How do we talk about autism?'
"It's tricky because autism is not one thing, because it is different for every single person who has autism.
"I would love her to be not Julia, the kid on Sesame Street who has autism. I would like her to be just Julia."
Sesame Street airs in the UK on Cartoonito, a pre-school channel from Cartoon Network.