Earle, 25, who was born in Durban, has been a prominent player with the Super 15 team this year making nine appearances.
The 6 ft 6" and 17st 5 lock has impressed in the Super 15 competition this year and is highly regarded as a first-class line-out jumper and dynamic in open play.
Contracts with the Cheetahs star were exchanged at 6pm last night (Monday) with Earle expected to conclude his season in Super 15 and arrive in Wales in July for the pre-season summer programme with his new club.
Earle represented Western Province at age-group level from 2005 to 2008, before making the step up to Vodacom Cup level.
The big lock forward moved from Cape Town to the Lions in Johannesburg in 2010, where he played for two years, before signing with Griquas this year.
Scarlets Head of Rugby Nigel Davies said: "This is a significant signing for the Scarlets, George is in his prime as a player and is ambitious to make a mark over here. He will bring a tough edge and different set of experiences from his career in Super 15.
"He gives a new dimension to our second row options and we know we need to enhance and strengthen our set piece play going into the big competitions next season, particularly in Europe.
"This is an important and exciting new addition to the Scarlets squad for next season. He's really looking forward to joining the group of players here at Parc y Scarlets, and keen to get his first taste of Northern Hemisphere Rugby and make an impact in the league and European competitions.
"It's key to have secured a quality second row, who at 25, has enough experience but also plenty to give and hunger to achieve over the next three seasons at Parc y Scarlets. He's an aggressive and focused player with a high work rate and has the ability to add a real edge to our game.
"We've said previously, that we wanted to take time to analyse our options carefully as a coaching group options and take the time to find the right solutions for this squad.
"We need to ensure that any players that are brought into our environment from outside our region, are the right fit for our progression and ambitions but also that could work with and complement the group of players we have here.
"As a coaching group, we have been working on this technical analysis for a number of months, so this move illustrates the level of player we are committed to recruit. To both strengthen the competitiveness of the squad and ensure we have the right level of senior players in key positions to help and mentor and develop a strong group of talented youngsters as we have done successfully previously with the addition of overseas players like David Lyons and Regan King."
The ambitious 25-year old lock has stated that an added boost of joining the Scarlets set-up is that he will have a chance to be considered for the Welsh national team - once qualified to play for his adopted country on completion of the three-year residency period.
ENDS
George Earle
Date of birth: 9th January 1987
Birth place: Durban
Height: 197 cm (6' 6")
Weight: 110 kg (17st 5lbs)
Guinness PRO12
Suite 208, Alexandra House,
The Sweepstakes
Ballsbridge, Dublin 4, Ireland