Webber will become head of content, controlling what goes on the ITV.com website, including news, gossip, soaps, dramas, kids, sports and entertainment.
Bradshaw has been appointed as head of online commissioning, in charge of producing material for the site externally and with a brief to help ITV.com build a reputation for having compelling content.
At IMG, she was director of production for new media, and was also part of the team that created the BBC's first on-demand broadband channel for BBC Two.
Bradshaw and Webber will report to Annelies van den Belt, managing director of ITV broadband, who said the appointments would "put us in a great position to continue the acceleration of ITV.com's traffic".