But that number was doubled thanks to Toulon's 16-15 win over Clermont Auvergne, with Giteau, Bakkies Botha and Danie Rossouw joining the exclusive club.
Giteau was just beginning his career when he lifted the Super Rugby crown with the ACT Brumbies in 2004.
And he made sure he savoured every moment of his latest success with the Cote d'Azur club.
"I got the Super Rugby title quite early in my career and I don't think I appreciated it as much as I do this one," said Giteau
"I didn't take it in as much as I should have. This time I really soaked it up through the week - took in the entire atmosphere.
"It means a lot to me and the team."
The former Australia star will be back in action on the weekend as Toulon face Toulouse in the semi-finals of the Top 14.
They could then face Clermont, who face Castres, once again and Giteau insists Toulon can do the double.
"Absolutely, with the spirit we have, if we celebrate the win and then work hard through the week." said Giteau.
"A lot of guys have their eye on the Top 14. This is a great win but we still have a job to do and hopefully everyone has their minds on that."
Heineken Cup and Super Rugby winners:
Matt Giteau (Brumbies 2004), Bakkies Botha (Bulls 2007, 2009) and Danie Rossouw (Bulls 2007, 2009, 2010) doubled the number of players who have done the double of winning a Super Rugby title and the Heineken Cup. Previously only three players had achieved the golden double - Rod Kafer (Brumbies 2001 / Leicester Tigers 2002), Doug Howlett (Blues 2003 / Munster Rugby 2008) and Brad Thorn (Crusaders 2008 / Leinster Rugby 2012).