The former X Factor USA presenter will join Nancy O'Dell on Wednesday and Thursday (March 28 and 29) on the CBS programme.
Jones confirmed the news on Twitter, saying: "This Wednesday and Thursday I will be guest hosting ET tonight with the wonderful @NancyODell.....this is going to be fun! (sic)"
He has previously worked with O'Dell while co-presenting Countdown to the Emmys on Fox last September.
The Welshman was axed after one season of presenting Fox's The X Factor USA.
He explained in December that hosting the show was more difficult than he originally thought.
Paula Abdul and Nicole Scherzinger will also not be returning to the talent show, with Britney Spears and Rihanna named as possible replacements.
The second season of The X Factor USA airs on Fox in September.
> Steve Jones uncomfortable on X Factor USA, says Alex Jones