McCaig was appointed chief operating officer of in 2003 and has been responsible for the group's operations throughout Europe. He was named chief executive of the company in 2006.
McCaig said: "Digital marketing plays an increasingly important role in the success of online commerce and it is a particularly exciting time for this growth sector.
"The industry is set to take an even more prominent place on the global stage and, as a leading-edge brand with a great history and pan-European footprint, bigmouthmedia is perfectly positioned to remain at the forefront of this fast evolving industry."
McCaig also previously worked as vice president of 3G operations at Nokia and spent seven years overall in the telecommunications industry.
Steve Leach, chief executive of bigmouthmedia, said: "We are particularly excited by the addition of Ian to our board.
"While his extensive experience in the online and technology sectors will deliver obvious benefits, his mastery of the mergers, acquisitions and integration process will be of great value as we enter the next phase in bigmouthmedia's development."