Polot.co.uk was launched in May by four former Guardian journalists.
Eva Lake, Lorna Willis, Will Ricketts and Ian Popeck have joined forces to set up the site, which received nearly 700,000 hits in its first month.
Lewis is helping Polot target Britain's one million Poles with their ‘One million minds on the move' initiative that seeks to keep Polish ex-pats up dated on news in their community.
Polot commercial director Eva Lake said: 'Lewis PR have given us invaluable advice on our PR and marketing strategy.
She added: 'They've helped us come up with our slogan of trying to reach "a million minds on the move", and with the messages we want to convey to the media world, to new users and advertisers.'