"I'm delighted to be offered this opportunity," the former Wales A and Ireland A coach told the rugby writers gathered at the press conference at Millennium Stadium.
"I'm a proud man today, but I'm well aware of the challenges ahead."
Ruddock said that in January, when he publicly pulled out of the race for the job, he wanted to see out his Dragons contract because of the "blood, sweat and tears" he had put into the role at the helm in Gwent.
"It had been tough work climbing the mountain with all the problems at the Dragons, and I didn't feel another mountain like the Welsh job was the right idea at the time.
"But when the Union knocked on my door, I couldn't say no. I see a bright future for Welsh rugby and I want to be a part of that."
Ruddock, a specialist forwards coach, will keep incumbent Steve Hansen's assistants, with Scott Johnson as backs coach and Andrew Hore as the fitness man. Ruddock's deputy at the Dragons, Clive Griffiths, is an option as the decision as to who becomes defence coach.
Ruddock described his team as "a perfect blend".
"We'll make slight adaptions to the way we're doing things to allow us to go forward - we have to get the basics right in Welsh rugby," he said.
"I back myself as a coach and believe in my ability as a coach - my ability has got me here and my determination has got me here."
Union chairman David Pickering declared: "We left no stone unturned in our search for the perfect man for the job.
"Mike has proved himself as a player, as a coach and as a man, and he has all the attributes necessary for this job."
Chief executive David Moffett added: "The other two men in the race were very strong candidates, but we wanted the best person possible to coach
Wales so we decided to see if Mike Ruddock was interested in the job."