As vice-president at Weber Shandwick, Yelland presided over clients such as Cadbury and Coca-Cola, and was public relations adviser to Tesco and BNFL.
Yelland is expected to join Brunswick in the autumn as a partner, focusing on the consumer sector including retail and luxury goods clients.
The company is City's biggest PR firm with 11 international offices and more than 300 staff, and was most recently involved in Greg Dyke's aborted £1.3bn takeover bid for ITV.
Brunswick, co-founded by Alan Parker, includes Hutchison Whampoa, Dairy Crest, P&P and BAA, among its clients.
A journalist for 20 years, Yelland was made editor of The Sun in 1998 and stayed in the role for five years, until current editor Rebekah Wade succeeded him.
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