A conditional contract for the freehold purchase of the Leicester Welford Road stadium from Leicester City Council was signed by the Tigers chairman Peter Tom at last week's board meeting.
The contract guarantees the stadium will be used only for sports activities for at least the next 13 years.
The sale, which will also include a section of the adjoining site of the former Granby Halls, has been hailed by city council leader Cllr Roger Blackmore.
"The terms of the contract will allow the Tigers to invest funds into undertaking substantial improvements to the stadium, which should keep the Tigers at this location for the foreseeable future," said Cllr Blackmore.
"Having such a high profile rugby club in the city brings many benefits, and I am delighted that the city council has successfully worked with the club so it will have the opportunity to substantially improve its existing stadium."
Peter Tom, Tigers chairman and major shareholder, said: "We are delighted to have finally concluded the purchase of the site and adjacent land.
"This is a milestone in the history of Leicester Tigers and will enable us to plan with confidence and certainty for the future."
The sale, further details of which have not been disclosed, was agreed at market value.