Bayliss, the former England coach who led them to the 2019 World Cup, has signed for three years and replaces Shane Bond at the Thunder after he opted against a contract extension to spend more time at home.
Saker, who has been a fast-bowling coach for Australia, England and Sri Lanka, will have the task of turning around the fortunes of the Renegades who have finished bottom in the last two seasons with just seven wins in 28 matches.
Both have previously been head coaches in the BBL. Bayliss was in charge of Sydney Sixers from 2011 to 2015 which included their title success in the inaugural 2011-12 season while Saker was a past Renegades coach for one campaign in 2015-16.
Bayliss, who is currently coach of Sunrisers Hyderabad in the IPL, is also a former New South Wales coach and was excited at the prospect of rejoining the cricket system in the state.
"It's great to be home and involved in New South Wales cricket," he said. "The Thunder have done well over the last few years… hopefully we can go one or two steps further this summer."
One of Bayliss' early jobs will be deciding on a new captain following the departure of Callum Ferguson who was not offered a new contract after last season.
Saker's deal is for two seasons and despite back-to-back wooden spoons since the club won the title in 2018-19 he is confident with the players that have been retained.
"We've got a talented squad with some class and power at the top of the order, complemented by a strong bowling attack and some exciting young talent," he said. "We'll be looking to add to this group over the next few months to ensure we've got plenty of options when the season gets underway.
"The Big Bash has continued to grow since my last involvement and it's more competitive than ever on the field so I'm looking forward to working with the playing group to ensure we give ourselves every chance of success."
Current Thunder squad Jonathan Cook, Ben Cutting, Matthew Gilkes, Chris Green, Usman Khawaja, Nathan McAndrew, Alex Ross, Daniel Sams, Tanveer Sangha, Chris Tremain
Current Renegades squad Cameron Boyce, Zak Evans, Aaron Finch, Jake Fraser-McGurk, Sam Harper, Marcus Harris, Mackenzie Harvey, Josh Lalor, Shaun Marsh, James Pattinson, Mitch Perry, Jack Prestwidge, Kane Richardson, Will Sutherland