Marmin Barba, 22, has been snapped up from the Gold Coast Titans on a two-year deal in a move that is also expected to help older sibling Ben find his feet when he begins life as a Bronco.
"Of course having two brothers together at the club can only be a positive for the two players and the Broncos," Brisbane football manager Andrew Gee said.
"We certainly view this as a win-win situation for all parties concerned."
The Barba brothers will join Martin Kennedy, Daniel Vidot and Todd Lowrie as new faces when Broncos pre-season training starts on November 6.
Gee said Marmin Barba had shown great character coming back from a knee reconstruction last year and lymphoma cancer treatment as a Parramatta lower grader at 19.
"We see some really good potential in Marmin," Gee said of the utility back.
"He has had to fight his way back from some setbacks, so he has shown some good character already.
"He had some trouble with illness and then his knee but he is all fine now."
Marmin Barba will spend the pre-season with the Broncos and will be aligned with feeder club Ipswich in the Queensland Cup.