The NSW Origin player will join the Titans from next season until the end of the 2016 campaign, after agreeing a signifcant deal.
Recent reports suggested Idris had been poised to sign Newcastle, but the 20-year-old said the lifestyle of the Gold Coast was a huge pull.
“I’m really excited about what the Titans have to offer as a club and the change of lifestyle on the Gold Coast,’’ said Idris.
“In saying that, I’ve enjoyed playing for the Bulldogs and I’ll be doing by best to make sure I finish my time with the club on a high.’’
The news is a boost to the Titans, who have won just one of their five matches so far this season.
Jetstar Titans Coach John Cartwright added: “Jamal is a great talent with size, speed and youth on his side.’’
“He has the X-factor and a real presence about him so I’m sure he’s going to make a real difference to our playing roster.’’