The 28-year-old play-maker has revealed he will join the Top 14 club following the World Cup later this year. But Giteau has only penned an 18-month contract and will return 'down under' in time for the visit of the Lions.
The motive behind the move is to prolong his career with the Wallabies and to sample a different rugby culture. He will join Lions' Jonny Wilkinson and Gavin Henson in the south of France.
''The intention is just to refresh myself,'' Giteau told the Sydney Morning Herald.
''It's to get away from the same old routines which you can get caught up in. If I'm still playing some great football, I'd love to come back to the Brumbies.
"You do need a break. You can get caught in the same routine year after year. But for me, even just training at the moment is exciting because I've known that I was going to go.''
And Giteau has vowed to go out on a high by helping the Brumbies to Super Rugby glory. They kick-off their season against the Chiefs on Saturday and will be lead by Giteau.
''I would want to win [the Super Rugby title] whether it was my last year or not," he explained.
"But I haven't made it a secret that I've signed. I'm happy it's done, but what I'm looking forward to is the Brumbies. I love this time of year and I love the Brums so I just want to make this as enjoyable and successful as I can.''