O’Donnell who is also the vice-chairman of Ogilvy & Mather Europe, Africa and Middle-East, and a member of the worldwide executive committee, will replace Michael Toedman on 1 July.
Toedman will remain a member of the UK board, taking responsibility for developing the global brand ThinkTank, which was first introduced into the UK chapter in 2008.
O’Donnell has been an active member of the UK chapter since January 2010.
He said: "I would like to thank my fellow IAA UK Chapter Board members for the confidence they have placed in me and will do my best to fulfil their expectations during my two-year term of office. I should also like to thank, in particular, Michael Toedman for his stewardship of the UK Chapter over the past four years."
He adds: "Since taking over from Peter Stringham of HSBC in January 2007, Michael has done much to improve and broaden the calendar of social and educational events which are the hallmark of the UK Chapter."
The UK chapter is one of the largest chapters of the International Advertising Association with more than 250 members. Worldwide, the IAA has more than 4000 members across 56 chapters in 95 countries.