Sinnock joined Asda from ad agency Fallon over a year ago and has since been responsible for UK customer marketing.
The move marked a return to brand marketing for Sinnock, who had previously had stints at O2 and NTL before joining Fallon in 2004. One of his biggest decisions in the role saw Sinnock shift Asda's £75m advertising account from his former employer to sister agency, Saatchi & Saatchi.
Asda moved quickly to appoint Owen, who will look to increase the marketing efforts around the Asda Price Guarantee and the We Sell For Less Programme. He will report into international chief marketing officer Rick Bendel.
Asda said Sinnock left the company 'to pursue his career beyond Asda'.