Llanelli RFC Limited has bought back the freehold to its Stradey Park home from the Welsh Rugby Union.
Stradey Park was sold to the WRU in 1997
One of Welsh rugby's most famous grounds was sold to the WRU for £1.25m in 1997, with the then cash-strapped club leasing the ground back.
The invoking of the buy-back option brings the move to a purpose-built new stadium one step nearer.
A proposed £20m development near the Trostre tinplate works will be a huge boost to the Scarlets regional team.
The new stadium development is a joint venture with Carmarthenshire County Council and will signal the end of nearly 125 years of rugby at Stradey Park.
Chief executive Stuart Gallacher said: "The buy-back of Stradey was critical to the whole scheme and now it has been achieved we are another step closer to our new home."