Adriaanse is the last of the seven summer signings to arrive at the West Wales region after completing his run in the Currie Cup this autumn.
A key signing for the Scarlets - particularly during the international window, Adriaanse adding more strength to their front five along with the signing of locks George Earle, Tomás Vallejos, Joe Snyman and Jake Ball.
The addition of Adriaanse to the squad gives a boost to the Scarlets pack for the rest of the season alongside experienced Scarlets international tight head Deacon Manu who has extended his contract at the region and now moves into his seventh season in Llanelli, together with fellow Scarlets Props Phil John (loose head) and Peter Edwards.
With these proven players adding weight to the front row, it also enables young, emerging Welsh players Rhodri Jones and Samson Lee (currently with Wales) and loose head prospect Rob Evans the opportunity to work closely with an experienced group of props and develop their ability further.
The 27 year-old Prop from MTN Lions is highly regarded as a technical scrummager and effective ball carrier with strong defensive skills and has been playing Super Rugby at the Lions for the past two years.
The Scarlets have secured a three year-contract for the sought-after tight head prop in late August. Adriaanse, who is 5ft 10in tall and weighs 18st 4lb, has also played for Boland Cavaliers, Cheetahs, Golden Lions and Griquas.
Scarlets Head Coach Simon Easterby said: "It's great to get Jacobie here now to join up with the squad - this is a key time in our season in terms of losing a number of our experienced players to the international squad - so we are sure that he'll have a positive impact for us going forward adding real strength to our pack.
"Securing someone of his ability and track-record is in line with our philosophy to carefully research, manage and target the right players to bring into our set-up. We want to add to and enhance the talent and experience we have here and bring players to the Scarlets shirt that fit with our ambitions over the next two to three years.
"These players need to contribute not only in terms of performance but also to the wider development of our squad - particularly our next generation players in the pack."
Jacobie Adriaanse, who knows fellow Scarlet George Earle well from playing U21s together at Western Province and Lions said: "This is a great opportunity for me to experience rugby in Europe and widen my experience in different competitions. I have obviously been watching as much Scarlets rugby as possible from overseas and I am impressed with the physicality and commitment the boys showed in their Heineken games and I hope I can add to that.
"From what I saw they've had some very intense, physical battles already this season and there is no doubting the spirit, pride and determination in this Scarlets team."
Adriaanse, who has previously travelled in the UK including Wales in 2005 on a home nations tour with Stallenbosch University said: "It appeals to me as well to experience a new way of life as well. I'm looking forward to the experiencing a different culture and community and my wife and I want to get as involved as we can with the club, its supporters and life in West Wales.
"We have had such a warm welcome already and only in a few days can see it will be easy for me and my wife to adapt to our life here and we are really excited to experience all that it has to offer."
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