Brough has started working at Lonely Planet in London but will relocate to the company's head office in Melbourne later this month.
Reporting to Matt Goldberg, Lonely Planet's chief executive, Brough will be responsible for leading Lonely Planet's online business and developing its digital strategies.
Brough joins Lonely Planet from Allegran Online Dating, where she was chief executive. In this role she managed a portfolio of sites and was responsible for building stronger marketing capabilities, including search engine optimisation, developing an affiliate network, growing display advertising and establishing partnerships with the Daily Mail and General Trust's web businesses.
Goldberg said: "Kelly brings to Lonely Planet a wealth of skills and experience which will further develop Lonely Planet's online business.
"She understands the significant opportunity to become the definitive source of travel information, tools and services for consumers online and I'm thrilled to have her onboard as we transform Lonely Planet into a leading multi-platform media company for the 21st Century."
Lonelyplanet.com, which relaunched last year, features Lonely Planet guidebook content, images, videos and maps covering over 8,000 destinations. It also allows users to book hotels and flights and share travel advice.
Brough said: "I look forward to building on the success of the website and other digital initiatives to deliver a really great experience that engages people and enables them to get to the heart of a destination wherever they are or want to go."