The move follows MerchantCantos' previous creative director Steve Hickson joining FleishmanHillard Fishburn.
Ireland was founding partner, chairman and CCO of Ireland Davenport (now CollectiveID) in Johannesburg from 2005, working with BMW, Vodafone, and Apple, among other clients. He left the agency in 2017 following its acquisition by WPP. He has also worked at BBDO, Leo Burnett, Ogilvy, and TBWA.
Ireland will oversee MerchantCantos' creative output from his base at the agency's London office in Lincoln's Inn Fields.
He said: "I am really excited to be joining the team at MerchantCantos and for the opportunities to develop large-scale societal campaigns that have lasting social impact for our clients."
Matt Shepherd-Smith, partner and chief executive, global, said the agency was going through an exciting period of growth.
"The changing nature of corporate communications and the evolving needs of our clients are clear evidence that we must offer broader creative thinking and execution in every area of the business," he added.