Derek McInnes has left St Johnstone to become manager at Bristol City on a two-and-a-half-year deal.
The clubs have agreed a compensation deal for the 40-year-old Scotsman, who leaves the Perth outfit after four years in charge.
City, who are bottom of the table, have been without a manager since Keith Millen's exit earlier this month.
"Derek was the unanimous choice," chairman Colin Sexstone told the Bristol City website.
"He's an impressive character who is very highly rated in the game and comes here on the back of a superb stint at St Johnstone.
"He's a manager on the up with a real understanding of the game. Derek has the drive and energy that proved to us he was the right man to take the club forward, both in the short term and - even more importantly - in the medium-to-long term."
McInnes, who brings with him assistant boss Tony Docherty, will be unveiled on Thursday and will take charge of his first game on Sunday against Birmingham City.
The former Rangers, West Brom and Millwall midfielder joined Saints as a player in 2007 and was promoted to manager after Owen Coyle left McDiarmid Park to join Burnley.
He then led the club to the First Division title in 2009 and promotion to the SPL.
McInnes rejected an offer to join League One outfit Brentford in May and also received interest from West Brom and Watford during their quest to find new managers.
St Johnstone are currently sitting fifth in the SPL table, while Bristol City have won just one game all season and have picked up just six points.
It is thought that McInnes was interviewed on Monday alongside former Barnsley boss Mark Robins and another unnamed candidate.
Meanwhile, coach Alan Walsh has left Ashton Gate after 11 years with the club.
A former City player, Walsh had worked with both the first team and in their academy set-up.