According to the Irish Times, under the deal, the retailer will continue to occupy the premises while paying the owner an annual rent of €950,000 (£823,802) for the next 15 years, effective from February 2019.
The deal is understood to have been completed recently.
Sports Direct also has the option to break the lease after 10 years, provided it gives one year’s notice. It will also be subject to rent reviews every five years.
It is just three years since the retailer purchased the property, which was previously occupied by department store Boyers, for a reported €12m (£10.4m).