Born in Kimberley, South Africa, the 26-year-old lineout and restart specialist is a formidable ball carrier in the loose thanks to an impressive athleticism, bound in a 6'5", 18st frame.
After following up promising showings in the Springboks U18 Academy, van der Westhuizen was called up to the Cheetah's U19 and U21 sides before progressing to the senior squad aged 24, with a Super Rugby debut against the Brumbies in 2010.
A groin injury meant he played only a handful of Super Rugby games during the 2011 season however, this year, he has returned to become a mainstay in the Cheetahs pack, starting all 12 of the club's matches this season.
His arrival completes the club's second-row stable, where he'll compete for a starting spot with recently re-signed trio of Sean Cox, Grant Gilchrist and Steven Turnbull, as well as fellow new boys Robert McAlpine and Perry-John Parker.
Van der Westhuizen, who (subject to visa) will arrive in October because of Currie Cup commitments, said: "I want to test myself against the top players in Europe so when I found out Edinburgh Rugby were looking for a player with my skill-set, I was desperate to sign.
"I like the pace the boys play with, it's very similar to a Super Rugby style which gives me a lot of confidence that I'll fit in well.
"I run the set-piece for the Cheetahs but, when the ball's in play, I like to be in the centre of the park getting stuck into the physical side of the game and hitting rucks.
"I'm really looking forward to joining the club. They've some real talent joining the squad and some quality Scottish players re-signed too so I think it's the ideal time to be part of a really exciting squad."
The South African joins fellow Cheetah WP Nel (prop) and former Junior World Player of the Year and All Black, Ben Atiga, on the long-haul flight to Edinburgh, where they will be met by seven other high-profile signings, including Welsh internationalists John Yapp (prop) and Richie Rees (scrum-half), Georgian World Cup number 8, Dimitri Basilaia, and English Premiership pair Greig Tonks and Michael Penn (full-back/wing).
Alongside the new arrivals, the club have retained 19 top-performing Edinburgh Rugby stars that have committed their futures to the club, pointing to a heightened belief in the bright future being forged at the Murrayfield club.
Head coach Michael Bradley said: "Over the course of this season we have been putting the right building blocks in place to tackle what is arguably the most eagerly anticipated season in the club's history.
"Reaching the Heineken Cup semi-final set the benchmark for our players' performance so we have recruited and retained a number of key players to bring consistency to our season and set a new standard for Edinburgh Rugby.
"The increased investment in our squad from Scottish Rugby will not only intensify the competition for places but means we will be on a much stronger footing to compete on all fronts, all season."
Izak van der Westhuizen (26) - second-row
Born: 23/01/1986 in Kimberley, South Africa
Height: 196cm (6'5"), Weight: 114kg (18st)
Rugby career:
Staats President Swart Primary School
Diamantveld High School
SA U18 development squad
Unversity of the Free State
Free State Cheetahs U19 and U21
Free State Cheetahs XV (debut v Brumbies, 2010)
Guinness PRO12
Suite 208, Alexandra House,
The Sweepstakes
Ballsbridge, Dublin 4, Ireland