The former representative superstar will remain with the club until at least the end of the 2018 NRL season, after trying his hand at the NFL in the US and sevens for Fiji since departing Parramatta in 2014.
"Not in my wildest dreams I ever thought I would be up on the Gold Coast," Hayne said.
The former NSW and Australian representative had previously committed to a "lifetime deal" with Parramatta when he left.
He said the decision not to return to the Eels was a hard one but he had still not received a formal offer from the club, which had been destabilised by the salary cap scandal, and needed to make a decision.
"A part of me is sad because I'm not going to go back to the club that I grew up with and loved as a kid," he said.
"At the end of the day I wanted to play footy this year.
"The way that the board is - the way things have gone this year, couldn't get something done, it's sad and it hurts me just as much as I know it hurts the fans down there."
Gold Coast coach Neil Henry said he wanted Hayne to debut for the club against the Warriors, however they would first need to assess his fitness.
"We expect he could take his place this weekend," Henry said.
"Subject to how he is feeling about his training and how many minutes and what position we can look at with respect to the guys doing the job there at the moment."
Henry also lauded the signing as a significant boost for the club's on-field hopes.
"We all know what a talent he is," Henry said.
"I know that our players are excited to be able to welcome him to the club and, more importantly, engage with him and see him on the footy field performing in the Titans jumper."
Titans CEO Graham Annesley said he was expecting a massive crowd a Cbus Super Stadium on Sunday for the chance to see Hayne's club debut.
The signing is a major coup for the Gold Coast club, which is soaring after being in disarray last year following the cocaine scandal and financial woes which forced it under NRL administration.
They still have significant salary cap space left after missing out on luring halfback Cherry-Evans when he walked out on a lucrative deal last year.
Cherry-Evans' deal was believed to be worth around $4 million over four years, however his backflip paved the way for the likes of Ash Taylor, Nathan Peats and Konrad Hurrell to join the club this year.
Off the back of the young stars the Titans now sit seventh on the table, despite coming into the season as one of the wooden spoon favourites.
JARRYD HAYNE'S NRL LIFE:
Born: February 15, 1988 (age 28)
NRL career:
Debut: May 19 2006, v PenrithGames: 176
Tries: 103
Honours: 2 Dally M Medals (2009, 2014), 3 Brad Fittler Medals (2007, 2008, 2014), RLIF player of the year award (2009).
Representative career:
State of Origin: 20 matches for NSW, nine tries
Australia: 12 matches, 11 tries
Fiji: 4 matches, 3 tries.
