Former Wellington Phoenix boss Rudan will lead Western United, set to enter the Australian competition as the 11th team in 2019-2020.
Rudan enjoyed a successful debut season in charge of Wellington – guiding the Phoenix to a sixth-place finish and their first Finals appearance since 2014-2015.
"It's an opportunity that couldn't be passed up," Rudan, 43, said. "To have a blank piece of paper to create what you want ... there's going to be some bumps on the way but I'm more than confident we'll see those through."
Western United has already signed former Australia international and Celtic striker Scott McDonald, 28-time Greece international Panagiotis Kone, ex-Besiktas defender Ersan Gulum and Sebastian Pasquali – who will arrive from Ajax's youth team.
Meanwhile, Adelaide United announced former Feyenoord boss Gertjan Verbeek as its new manager.
Verbeek – who spent a year in charge of Eredivisie giant Feyenoord before stints with AZ, Nurnberg, Bochum and FC Twente – replaces Marco Kurz on a two-year deal.
"I am very excited to be joining Adelaide United and cannot wait for this incredible opportunity to begin," the 56 year-old Dutchman said. "I have followed Australian football for a while now and have admired the work ethic and passion Aussies have for the game.
"I am coming to South Australia to improve the quality of football and establish a hungry and competitive team. I can promise the Adelaide United fans that our team will be incredibly hard-working and hope to entertain you all with some high-quality football.
"As I said, I am very excited for this journey and my family and I are very eager for it all to start."