Vega Olmos will report to Bob Jeffrey, worldwide CEO of JWT, and will partner with JWT Europe CEO Toby Hoare, Latin America president Jimmy Evans, and executive chairman of JWT Brazil, Stefano Zunino.
Dividing his time between Spain and Argentina, Vega Olmos will join his partners in steering the work, recruiting creative talent and working on JWT's multinational clients in the two regions.
Vega Olmos joins JWT from Lowe Latina, where he has been chairman since early 2007, having joined the agency at the end of 2004 as Unilever worldwide creative director.
He began his career as a copywriter at Gowland & McCann Erickson, moving to Ratto BBDO where he was creative director and then on to Casares Grey as executive creative director and partner. In 1992 he became the first Argentinian creative to win a Gold Lion at Cannes.
In 1997 he launched VegaOlmosPonce in Buenos Aires with Hernan Ponce, creating campaigns that aired in Latin America, US, Europe and Asia.
Jeffrey said: "Fernando Vega Olmos is widely regarded as Argentina's most revered creative and we are thrilled to welcome him to JWT Worldwide.
"With Fernando in place, JWT will offer clients an unparalleled roster of creative talent across all markets."