The 33-year-old powerhouse had been a free agent after his five-month deal with Super Rugby franchise the Stormers came to an end.
The 96-cap Wales and Lions international will be signing with the Dragons, seven years after leaving Wales.
This is despite significant interest from all over the world, with the 33-year-old receiving offers from Major League Rugby, Japan, Leicester Tigers and Edinburgh to name a few.
Dean Ryan, Director of Dragons Rugby, said: “It’s great news that we are bringing someone of Jamie’s quality to the region and we know he will make an immediate impact for us.
“He remains an ambitious and driven player and is looking forward to coming into our environment.
“To have his experience on the pitch will be a great addition to us, and he will also be an excellent mentor for the younger players in our squad.”
Roberts spent the first six years as a professional in the Welsh capital with Cardiff Blues, and the list of locations he has ticked off since leaving in 2013 have been enviable.
Paris, London and Bath have been his homes over the past seven years.
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UPDATED | British & Irish Lions predicted 2021 starting XV, according to the bookies
Odds are accurate on Wednesday,3rd July, 8am, and are subject to change.
Fullback:LIAM WILLIAMS (Wales 4/7)
Other contenders: Stuart Hogg (Scotland 4/6), Jordan Larmour (Ireland EVS), Leigh Halfpenny (Wales 5/1), George Furbank (England 7/2)
Left wing:JONNY MAY (England 1/25)
Other contenders: Jacob Stockdale (Ireland 1/3), Adam Radwan (England 40/1), Jack Nowell (England 11/4), Louis Rees-Zammit (Wales 13/8)
Outside-centre: JONATHAN DAVIES (Wales 1/3)
Other contenders: Henry Slade (England 5/6), Garry Ringshow (Ireland 4/6), Jonathan Joseph (England 13/8), Chris Harris (Scotland 20/1), Huw Jones (Scotland 6/1)
Inside-centre:MANU TUILAGI (England 1/3)
Other contenders: Robbie Henshaw (Ireland 5/6), Hadleigh Parkes (Wales 5/4), Sam Johnson (Scotland 9/2)
Right wing: JOSH ADAMS (Wales 1/18)
Other contenders: Anthony Watson (England 4/6), George North (Wales 2/1), Elliot Daly (England 10/11), Joe Cokanasiga (England 3/1), Keith Earls (Ireland 9/2)
Fly-half:OWEN FARRELL (England 1/25)
Other contenders: Johnny Sexton (Ireland 1/2), Dan Biggar (Wales 8/15), Finn Russell (Scotland 3/1), Marcus Smith (England 8/1)
Scrum-half:CONOR MURRAY (Ireland 4/6)
Other contenders: Tomos Williams (Wales 5/4), Ben Youngs (England 6/4), Ali Price (Scotland 2/1)
Looshead-prop: MAKO VUNIPOLA (England 4/6)
Other contenders: Ellis Genge (England 1/3), Cian Healy (Ireland 5/6), Joe Marler (England 5/2)
Hooker:JAMIE GEORGE (England 1/10)
Other contenders: Luke Cowan-Dickie (England 4/6), Ken Owens (Wales 7/4), Stuart McInally (Scotland 7/2)
Tighthead-prop: Tadhg Furlong (Ireland 1/15)
Other contenders: Kyle Sinckler (England 1/5), Tomas Francis (Wales 11/8), Harry Williams (England 5/1)
Lock: MATO ITOJE (England 1/10)
Other contenders: James Ryan (Ireland 1/5), Jonny Gray (Scotland 8/11)
Lock: ALUN WYN JONES (Wales 1/5)
Other contenders: Iain Henderson (Ireland 4/6), Courtney Lawes (England 5/4), George Kruis (England 7/2), Jean Kleyn (Ireland 33/1), Richie Gray (Scotland 5/1)
Blindside-flanker: TOM CURRY (England 1/7)
Other contenders: Peter O'Mahony (Ireland 7/4), Lewis Ludlam (England 11/4), Jamie Ritchie (Scotland 10/1)
Openside-flanker: SAM UNDERHILL (England 1/4)
Other contenders: Hamish Watson (Scotland 8/11), James Davies (Wales 10/1)
Number 8: BILLY VUNIPOLA (England 1/4)
Other contenders: CJ Stander (Ireland 1/3), Taulupe Faletau (Wales 11/10), Ross Moriarty (Wales 5/1)