Al-Qassab takes over the reins from temporary chief Zillah Byng-Thorne on 1 June.
Jenner will remain as Wavemaker global chief executive.
Johnson & Johnson to sell off its remaining 9.5% stake in Kenvue.
Nannette LaFond-Dufour will report to global boss Arthur Sadoun.
Organic revenue was up 2.4% in Japan.
Sir Martin Sorrell said that the group will continue to capitalise on AI positioning.
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