The 54-year-old engineer left the German squad over the winter to return to Williams where he worked almost three decades ago, from 1987 to 1993.
While Lowe assumes the role of chief technical officer, as a shareholder he also now enjoys a seat on Williams' board of directors, a prominent position which apparently eluded him at Mercedes.
Lowe has no doubts a customer team can win the world title, with Red Bull racing serving as a perfect example of such an achievement.
"Yes. I mean the engines are actually all the same between the different Mercedes teams, they are supposed to be between all engine suppliers," Lowe say in a meeting with the media on Thursday.
"So it's absolutely possible to win a championship. There's no better example of that than Red Bull who have done very well with the Renault engine when they were not classified as a works team."
Claire Williams has hailed Paddy Lowe's arrival at Williams as a 'game changer', with the Grove-based outfit eager to optimize its development. Lowe is looking forward to the challenge.
"It's a great opportunity, I think that's the simplest way to put it. We achieved incredible things at Mercedes in three years and, of course, they may continue to do so.
"I'm very proud of the part I played in that set of championships, but for me personally a great opportunity came up at Williams and I'm very excited about it.
"It's been discussed many times the disparity of funding between teams in the pitlane so clearly it's more difficult to compete at the front when you have less money, nobody will deny that.
"The challenge here is to make the most efficient use we can with the resources we have. In parallel you're constantly trying to gain access to more resources that's what drives success in this sport.
"Do a good job, generate more income so you can do an even better job. If we want to move forward we have to move forward technically and then financially when you make all of those factors contribute together."