Stuart Lorimer is swapping working with Johnnie Walker and Smirnoff for looking after Irn-Bru and Rubicon as he joins the board of the Cumbernauld business.
Mr Lorimer, 47, who studied at Glasgow University, is a chartered accountant who spent time with KPMG before joining Diageo.
In his 22-year career with the drinks giant he has served in a number of roles covering marketing, commercial and corporate finance functions.
At the moment he is the finance director of the group's £4 billion global supply operations.
AG Barr saw its current finance director Alex Short announce his intention to take up the same role at spirits company Edrington earlier this year. Mr Short will leave AG Barr at the end of this month.
Headhunters were employed to identify his replacement with a "full and proper" process looking at a range of candidates carried out.
Mr Lorimer is understood to have a six-month notice period but AG Barr are hopeful he will formally join the business once a handover period at Diageo is completed.
Roger White, AG Barr chief executive, said: "Alex leaves the business shortly with our very best wishes to take up his new role at the Edrington Group.
"We are delighted to announce the appointment of Stuart Lorimer, who is an outstanding finance professional."
AG Barr recently reported sales revenue was likely to be up 5.6 per cent in the first half of its financial year.