Johnson filled in during Monday night's show and will take over again Tuesday night. Andrews is expected to return on Oct. 3.
Johnson, who had appeared as a professional dancer on the series, is the host of the live online interview show, DWTS: All-Access.
"Thank you to my @DancingABC Family for supporting me while I take the week to be w/ family," Andrews tweeted. "Can't wait to be back in the ballroom next week!"