The firm, which was founded in 2001 by its chief executive Alison Sellar, provides payroll services and online HR management tools to more than 1,000 companies in some 140 countries. It has additional offices in Australia, Singapore, Dubai, South Africa, Germany, France and the US.
London-based Tenzing Private Equity targets investments in high-growth businesses across the UK and Ireland.
Sellar said: “Over recent years Activpayroll has expanded significantly whilst maintaining an extremely high level of customer satisfaction and this must be attributed to the Activpayroll team. We look forward to working in close cooperation with the Tenzing team and accessing their growth eco-system to continue the exciting Activpayroll journey.”
Guy Gillon, managing partner at Tenzing, added: "We are as excited as the Activpayroll team about the next stage of their impressive journey and share their significant ambitions for the business."