Mike Ashley has promised to turn House of Fraser into the "Harrods of the high street" after buying the company for £90m.
Sports Direct issued a statement confirming that the acquisition includes all the UK stores, the brand and all the stock.
It comes after the department store chain announced this morning that it is to appoint administrators after it failed to find a solvent solution.
Mike Ashley said: "This is a massive step forward and further enhances our strategy of elevation across the Group. This will benefit both House of Fraser and Flannels in the luxury sector. We will do our best to keep as many stores open as possible.
"It is vital that we restore the right level of ongoing relationships with the luxury brands. Our deal was conservative, consistent and simple. My ambition is to transform House of Fraser into the Harrods of the High Street."
The price paid for the chain represents a heavy discount for the once-mighty department store.
In the year to 28 January 2017, House of Fraser had assets worth almost £950m. It was bought by Chinese company Sanpower four years ago in a deal that valued the business at £450m.
City A.M. understands that retail billionaire Philip Day, the owner of Edinburgh Woollen Mill, had made an alternative offer for the chain that would have paid £100m, which had the support of a group of suppliers.
Retail observers have even previously suggested that Ashley could merge House of Fraser with Debenhams, in which he holds a stake of just under 30 per cent.
Shares in Debenhams jumped more than three per cent this morning as news of House of Fraser's insolvency emerged.
"This would be an exciting development for the retail sector as it could effectively consolidate the two troubled department store chains into a single offering," said Neil Wilson of Markets.com about the prospect of a combination.
"This appears the only viable solution; combining the operations to reduce overheads and stop competing against each other after a pretty brutal period of sales that has hammered margins."
"City A.M. understands that retail billionaire Philip Day, the owner of Edinburgh Woollen Mill, had made an alternative offer for the chain that would have paid £100m, which had the support of a group of suppliers."