The arrival of the 29-year-old lock will be a major boost to the Scarlets as they prepare for the new season which includes a difficult Heineken Cup draw.
The transfer of Louw from French side Clermont Auvergne looked to be in jeopardy under new regulations brought in on February 8. But the Scarlets successfully appealed to the Home Office as Louw was signed before the regulations came into force.
Scarlets Chief Executive Stuart Gallacher was pleased to have wrapped the drawn out deal up. He said: "We're delighted and looking forward to Hottie joining us in a few weeks."
The Scarlets will face Heineken Cup holders Toulouse, former champions Wasps and Scottish outfit Edinburgh following last week's draw for the pool stages of next season's competition
WRU Consultant Head of Physical Performance Paul Stridgeon praises the Physical Performance department for their work and dedication as he addresses the media ahead of Wales' Pool A clash against Australia
Twelve young people have been selected to follow a one year WRU Coach Core apprenticeship programme. Coach Core was set up by the Royal Foundation of the Duke and Duchess of Cambridge and Prince Harry as part of the Olympics legacy in 2012 and the Duke of Cambridge was on hand to meet the apprentices on their first day in the job. The programme has been funded by the Hunter Foundation.
The WRU has launched a campaign to create a long term legacy for Welsh club rugby by highlighting the advantages of volunteering. Rhian Edwards, a volunteer at Seven Sisters, has enjoyed many benefits of her volunteering at a grassroots rugby club including being part of the Rugby World Cup volunteer workforce after being nominated by the WRU - and the WRU is asking for more people to develop their 'Welsh rugby roots'.