The Sports Direct boss has been summoned due to allegations about working practices at the company's Shirebrook warehouse in Derbyshire.
Last Friday it emerged he would not turn up at the meeting scheduled for Tuesday because his lawyer Richard Gordon QC could not attend; but today he changed his mind.
In a letter to BIS committee chair Iain Wright, Ashley wrote in capital letters that he had "nothing to hide", adding: "I believe my repeated invitations for you to attend Shirebrook are a clear demonstration that in fact we have nothing to hide. I was merely seeking to avoid an unnecessary media circus".
Wright said: "I'm pleased that Mr Ashley has finally agreed to give evidence at our hearing on Tuesday.
"Mr Ashley announced in December he would personally oversee a review of working practices at the Shirebrook warehouse in response to serious allegations made and we look forward to Mr Ashley answering our questions, including in response to these allegations and the progress of his review.
"As a committee, we want to get a sense of the genuine and balanced picture at Sports Direct and establish whether there are issues for the wider economy which need further examination, such as the status and rights of agency workers."
When Ashley initially refused to show, Wright said: "Mr Ashley announced in December he would personally oversee a review of working practices at the Shirebrook warehouse. It is entirely reasonable for the select committee to ask Mr Ashley to respond to those allegations and comment on how his review – announced over six months ago – is progressing.
"Business leaders regularly come before the Committee and answer our questions. Sir Philip Green, for example, has agreed to attend as part of our joint inquiry into BHS.
"Does Mr Ashley, owning and operating a business in a parliamentary democracy, see himself as being beyond such public scrutiny? What has he got to be frightened of?"