The move coincides with a wider-ranging management rejig at the agency.
Liz Belinska, who was previously the president and executive committee member of Omnicom's Martin Williams agency in the US, is joining the Manchester-based shop to replace McDonald.
She will work alongside Nick Brookes, who has been promoted from his role as joint managing director to sole managing director.
Brookes' former managing director partner, Carol Smith, has been appointed to the newly created role of group business development director. She will work across all of TBWA's Manchester operations: Tequila\Manchester, BDH\TBWA and the Manchester office of Staniforth.
Meanwhile, the account director Alexandra Johnson has been promoted to marketing director. She replaces Dave Peters, who will move to head BDH's integrated marketing services division.
BDH's chief executive, Neil Griffiths, made the changes. He said: "This team will ensure BDH\TBWA delivers at all levels and provides the talent and ambition to drive the business forward now and in the future."