Vea, 27, who played for Tonga in the 2009 Pacific Cup, began his NRL career with Cronulla in 2009 and also played for Melbourne before moving to the Dragons.
Broncos head coach Tony Rea said: "The squad is delighted to welcome the hard-working and skilful attributes that Atelea brings to games."
Rea, whose side went down 44-18 to Salford in their opening home game on Saturday, is still re-building his squad following the move to Barnet.
The Londoners, who are also being linked with Vea's St George Illawarra team-mate Josh Drinkwater, have confirmed that Leeds youngsters Alex Foster, Thomas Minns and James Duckworth will remain with the club for the rest of the season after iniitally joining on loan.
All three are contracted to the Rhinos from 2015 onwards.
- Sports & Recreation