Powell last featured in the PRO12 for Cardiff Blues - Wales skipper Warburton's side - back in 2010 before moving across the River Severn.
Following spells with Wasps, Sale Sharks and rugby league side Wigan Warriors the 32-year-old, who won 23 caps for Wales, has linked up with the Dragons as they seek to improve on a ninth-place finish last season.
That was just two spots back from the Blues and Warburton is expecting Powell's new side - led by Kingsley Jones - to enjoy a productive new campaign.
"It's an awesome move and a great signing by the Dragons," Warburton told the South Wales Argus. "To have Andy, Toby Faletau and Lewis Evans, that's a really tasty back row
"With the other signings they have made this summer the Dragons will be even more competitive this year and I am sure they will have a good season.
"It's great that players are coming back to Wales and everybody who has met Andy loves him."
And it is not just on the pitch where Warburton expects Powell - a 2009 tourist to South Africa with the Lions - to have an impact at Rodney Parade.
"He will be a great addition for the Dragons and you know that he will bring aggression and physicality," he added.
"Andy is also a really good trainer and that will rub off on the rest of the guys. He spends a lot of time in the gym and on the training pitch doing extras, so is a great player to have in the squad."
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