Havas Work Club previously worked on the account but lost it when Sharp pulled out of the European market last year.
The agency has been tasked with helping Sharp deliver "greater convenience, service and sustainability".
It will work on digital and social activity, and there are plans to introduce print and digital ads later in the year.
Sharp has pledged to provide constant customer service, Twitter support and next-day call-outs.
Paul Molyneux, the European managing director at Sharp, said: "When we set out, we observed in Europe that more than 3,400 customer complaints about home appliances go unanswered on Twitter each week.
"Our competitors are not listening. We saw that we could dramatically shake up the home appliance industry if we put the needs of our customers first."
In 2012, Work Club launched Sharp FanLabs to support the brand’s sponsorship of Euro 2012.