Cairns will take up the newly created role of chief executive at Love in July after only joining Phones4U in December.
He is leaving to go agency side after spending around 20 years as a client and almost 13 years at Nike.
At Nike Cairns was chief marketing officer at Umbro for four years up until its sale by Nike to Iconix Brand Group late last year. During his time at Umbro Cairns worked with Love on projects spanning branding, advertising, experiential and digital.
Cairns has also worked for Nike as general manager of the UK and Ireland business and was responsible for running football marketing for the EMEA region.
Love’s clients include Diageo, Nike China, Virgin Media and recently launched Chinese auto brand Qoros. Cairns said: "This will be my first role in an agency and I’m looking forward to bringing a new perspective to the talented team I’ve already worked closely with as a client, as well as helping the business to develop and grow in the future."