A cornerstone of the Free State Cheetahs' pack, the 6'5, 18 stone, second-row started every game in this season's Super Rugby and Currie Cup championships, where helped the club retain its Premier Division status in his last outing.
Despite missing only 40 minutes of rugby in 30 competitive games (as well as three warm-up fixtures), the 26-year-old stalwart assured fans he's desperate to bring his match fitness to the club's cause in the RaboDirect PRO12.
Van der Westhuizen, who arrived with his wife Bonita, is the third southern-hemisphere signing at the club this season, following fellow Cheetahs prop Willem Nel, and former Highlanders centre Ben Atiga from Super Rugby in the summer.
He said: "I've played a lot of rugby this season but I'm keen to meet up with the boys and get into action as soon as possible.
"I'm really excited to be here. It's a new challenge and I'm looking forward to being part of a great club with a good attacking style.
"It's often said that the PRO12 and Heineken Cup are the most physical competitions in the world, so I'm looking forward to seeing how it compares with my experiences in the southern hemisphere.
"I consider myself a pretty physical player, particularly in the tackle and contact areas, clearing out rucks and so on, while my lineout work is also something I pride myself on.
"I've spoken to Willem [Nel] since he arrived and he's told me how professional the set-up is and how welcome he's been made to feel.
"I'm really looking forward to my first match in the black and red of Edinburgh Rugby."
Izak van der Westhuizen will undergo a medical at Murrayfield Stadium this afternoon and is expected to be available for selection for this Friday's match against Ulster at Ravenhill (kick-off 7.05pm).
Izak van der Westhuizen (26) - second-row
Born: 23/01/1986 in Kimberley (South Africa) - Height: 196cm (6'5"), Weight: 113kg (18st)
Rugby career:
Staats President Swart Primary School and Diamantveld High School
SA U18 development squad, University 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