McInnes has signed a contract with the npower Championship strugglers until summer 2014.

"Derek was the unanimous choice of the board of directors and majority shareholder," Sexstone told the club's official 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."

McInnes, who will be formally unveiled as the Ashton Gate outfit's new boss tomorrow, led St Johnstone to promotion to the Scottish Premier League in 2009 and leaves them in fifth place in the table.

Sexstone added: "His passion, his great track record, 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.

"Throughout this process we received applications from a host of very strong candidates but in the end Derek stood out above all others.

"I'm sure our supporters will give Derek their full backing, starting this Sunday for our home game with Birmingham City, as we begin a new era and strive to move up the Championship table and beyond."

Former Scotland midfielder McInnes' first managerial job in England is certainly a tough challenge.

He succeeds Keith Millen in charge of a side who are rock bottom of the table, have won just once in 12 league games and not tasted victory at home in any competition this season.

The Robins are just two points behind second-bottom Doncaster, though, and four from safety.

McInnes has kept St Johnstone in the SPL for the past two seasons and survival will be the primary objective at City.

Saints chairman Geoff Brown conceded a fortnight ago that the Perth club would find it hard to hang on to him.

He told the Daily Record: "The wages in the Championship make the money St Johnstone can afford to pay a manager look insignificant.

"When (former St Johnstone manager) Owen (Coyle) won Burnley promotion (from the Championship) I understand he got a bonus that set him up for life.

"If the downside of having young managers who make St Johnstone successful is that other clubs are attracted to them I can't make apologies for that.

"It's better to lose your manager than have to sack him one day."