Ray Bradbury never won an Oscar, but in 1963 he came close.
The 1962 short film Icarus Montgolfier Wright, which animated hundreds of Joe Mugnaini's paintings, was written for the screen by Ray Bradbury and George Clayton Johnson, and based of course on Ray's short story. It was nominated for an Oscar in the category of Best Short Film, and the award would have gone to producer Jules Engel. But on the night, the award went instead to John and Faith Hubley for The Hole.
Here's the announcement of the nominees and winner, from actor Van Heflin: https://www.oscars.org/vef/load/575b1f3cc94322f3e3173d907ac0ca12?width=640&height=365
You can watch the Hubleys' film here: https://www.youtube.com/watch?v=PGB3eudJwOU
And you can watch Icarus here: https://www.youtube.com/watch?v=lm5kylavY3Y