Costigan said he is looking forward to a fresh start with the Raiders, and is excited about where the club is headed in the future.
"It will be good to start again and get my football back on track," Costigan said. "I think the Raiders have a great future with a great bunch of young players and a lot of talent coming through."
Costigan said he is looking forward to renewing some new friendships with some of his former teammates and opponents, and also meeting the Raiders crop of young stars.
"I have played with and am good mates with Tom Learoyd-Lahrs from our days at Brisbane, and have also played with Craig Frawley and against Dane Tilse, so to play with these guys will be great," he said. "I think with the players they have at the moment and the guys developing, there is a big chance that we could win a grand final."
With the Raiders about to embark on a new age under a new Coach in Neil Henry, Costigan said he is ready to work hard for his new mentor.
"Neil seems very genuine and I'm looking forward to having him coach me next year," he said. "He said if I work hard and have a big off-season I will be chance to start the year in the back row and that's what I want to do."
Raider's co-assistant coach David Furner said the Raiders are looking forward to Costigan arriving in the nation's capital, and his connection with some of the players will see him settle in quickly.
"I think the club has done a really good job of securing Neville," Furner said. "We have been looking at him for a while and he has a good connection here with a good friend of his in Tom Learoyd-Lahrs."
Furner said the Raiders will present Costigan with an exciting chance to build a career with the club, and explained to him the future plans for the Raiders when negotiating his contract.
"The Raiders will give him a good opportunity to play first grade, and he will be a good asset for the club," he said. "I think one of the things that was explained to him was what the club was trying to achieve with getting young players here, and one of the policies that club has is to look to the future.
"All the players at the start of next year will be on a level playing field, and Neville will be one of those guys looking for a first grade jumper."