
O'Leary, currently director of customer service at Carphone Warehouse, will join Orange next month in the board-level role.
She succeeds Mike Hughes, who is taking up the new role of vice-president of transformation.
O'Leary's appointment follows Orange's launch of its new agenda in June, which laid out plans to improve, grow and evolve the company.
Tom Alexander, chief executive of Orange UK, said: ‘With over 20 years of experience in the mobile, broadband and other industries, Jackie is key to us hitting our ambition of becoming the UK's best-loved communications brand.'