Pike has held a number of executive-level positions in the online industry with a focus on setting industry standards and developing the online medium.
His most recent role was as chairman of the Australian Internet Advertising Bureau's sub-committee for online measurement.
Pike will be based in Nielsen Online's regional offices in Sydney, Australia.
Megan Clarken, managing director of the Pacific region at Nielsen Online, said: "Stuart is a seasoned industry expert and he is joining us at an exciting time for the evolving media sector.
"His knowledge of the online space and the needs of the market will be invaluable in providing important analytics services that support the ongoing growth of the industry."
Pike said: "It's an exciting time for both Nielsen as well as the wider online industry in Australia and New Zealand. I look forward to working with clients to implement solutions that will enable them to best understand and improve the performance of their business."