Whiteley will work across a number of accounts at the agency, including Littlewoods, Makro and Matalan, having previously worked with Nissan and Citibank during her time at TBWA\Manchester.
The agency has also hired Caroline Davies, formerly brand manager at Royal Mail, as a specialist account manager. She will be responsible for developing third party business for Matalan and fitness website .
If Agency, which also handles work for Tetley's and Odeon, said the appointments would aid the development of its online marketing business.
Christian James, managing director of If Agency, said: "Having worked with Jo at TBWA, I knew from the outset that she would be exactly the right person for this crucial role. As an unconventional direct agency, our ideas need to exploit all contemporary channels and Jo can help us do that.
"Caroline brings a level of professionalism to the role that means both strategic and commercial objectives are achieved in each partnership."