The winger played in three of Tonga's World Cup group games including the shock defeat of Sunday's finalists France.
At 5ft 8in, Iongi provides a different option to giant wing George North but is also able to fill in at full-back.
Davies is adamant the Scarlets' commitment to producing Welsh talent is as strong as ever but admits with four of his backs involved in Wales' third-place play-off they need to have the cover in their RaboDirect PRO12 campaign.
He said: "We are delighted Viliame Iongi is joining us - I think he will give us an exciting new dimension.
"He is certainly an exciting prospect for us and his attacking ability will fit in with the style and brand of rugby we seek to play. He's impressed with his pace and will provide us with some new options.
"The Scarlets are proud of the investment our region has made over the past two to three years in bringing forward and progressing new Welsh talent - which has been so evident from the impact of our Scarlets for Wales' in the World Cup.
"However, the success of our development pathways and progression of our home-grown players to first choice international players means we have to plan carefully - considering the impact on our regional squad during international windows with a core of our squad away at key times within our season.
"Our firm vision and commitment is to bring forward our own talent - investing in our young players and giving them chances at the highest level with full support from within our rugby environment.
"We also recognise that we'll require additional players from outside our region who can bring specific skill sets and experience to anchor the squad during the time we lose our players to international commitments."
Iongi is due to join the Scarlets at the start of November and could make his bow in the Heineken Cup campaign.
And he believes the Scarlets' commitment to attacking rugby is tailor-made to his attributes.
He said: "It's is a great opportunity for me and as my first professional rugby contract, I'm now going to get the chance to play in Europe and hope the way I play will fit in well with their style.
"I'm looking forward to being part of such a professional set-up and will give it everything I can. The Scarlets play great rugby and I'm looking forward to being part of the team."
63x46.png){kind=logo}