Arnold signed an upgraded deal with the Brumbies and Australian rugby on Friday, ending speculation he was set to join French glamour club Toulon on a lucrative contract.

The tallest player in Australian rugby history says he opted to stay in Canberra to be part of a Brumbies rejuvenation and the Wallabies' World Cup campaign in 2019.

It is hoped outside centre Tevita Kuridrani will join Arnold in recommitting to the Brumbies as cashed-up European clubs circle Australian stars as signing targets.

Arnold had the chance to join some of the biggest names in rugby — including former Brumbies skipper Matt Giteau — at a club known for big contracts and star power.

"But I think I made the best decision moving forward for myself and for my family," Arnold said.

"The money overseas is obviously big and it is tough because you do weigh up things, but there's the World Cup in 2019 and trying to get to that.

"I still feel I've got more to give here, so I didn't want to make a decision to head to Europe too early, that was a big part of me hanging around in Australia for a few more years."

Arnold still had one year left on his contract with the Brumbies, but the club acted fast to ensure the 208-centimetre second-rower would remain in the capital.

European clubs launch their raids on Australia's player ranks in December and January to fill their rosters and they've got more cash than Super Rugby teams.

However, the lure of Wallabies gold is still a key factor in negotiations and Arnold is determined to cement his place in Australian rugby.

Arnold has enjoyed a quick rise to the top, breaking into the Brumbies squad last year and making his Wallabies debut this season.

"I'm by no means an established Test player or anything like that, I'm still pretty confident my best footy is ahead and I'm looking forward to the challenges of getting better," Arnold said.

"I thought I had a pretty solid year in my first season, but I didn't want to fall away straight away in that second season.

"I didn't want to be happy with doing the same as the year before, I want to improve and challenge myself and that's what I'm looking for again.

"I don't think I would play for another Australian Super Rugby franchise, the Brumbies were the ones that gave me a chance in Canberra and I wanted to repay the faith."

Arnold has committed to the Brumbies despite not knowing who the coach will be in the 2018 and 2019 seasons.

Stephen Larkham will finish his tenure at the end of next season and the club will begin its search for a replacement when new chief executive Michael Thomson steps into the role in January.

The Brumbies are also coping with a leadership vacuum after the departure of Stephen Moore, David Pocock and Matt Toomua. Christian Lealiifano will also miss the 2017 season through illness.

But Arnold is confident a new generation can stand tall to continue the Brumbies' run of four successive finals appearances.

"If you look at all the players we've lost over the last couple of seasons, the Brumbies are in a bit of a rebuilding phase," Arnold said.

"So things do change when you lose all of those players and that experience. But it's also good because it's a new challenge and our squad is looking a lot different.

"I'm happy to be a part of it, we'll build and it will be exciting to see some of those young Canberra boys coming through."

Arnold and the rest of the Brumbies Test contingent will return to Super Rugby training on January 5.