The travel management company has taken 5,900 sq ft in Bruntwood's Manchester One on a 10-year lease.
The firm, which specialises in the charity and not-for-profit sector, was previously based at Hanover House in Charlotte Street.
Bruntwood has recently invested more than £2m to redevelop the 21-storey building on Portland Street.
Sarah Burrows, director at Diversity Travel, said: "We have plans to expand the business and working with a property owner such as Bruntwood provides the perfect partner to accommodate our future growth and environmental values."
DTZ acted on behalf of Diversity Travel.
Simon Roddam, office agency senior surveyor at DTZ, said: "Whilst there was a healthy supply of office accommodation in Manchester city centre within Diversity Travel's size criteria, it was Bruntwood's Manchester One offering that provided our client flexibility for growth, a sustainable and creative working environment, on competitive lease terms."
Bradley Topps, city centre surveyor at Bruntwood, said: "We are pleased to have the opportunity to work closely with DTZ to provide a property solution that meets the requirements of Diversity Travel.
"Diversity Travel had a number of bespoke requests in relation to the specification of their office space to enhance the sustainability of their working environment, which was refreshing to hear. From energy efficient LED lighting to 95% recycled carpeting, the customer has added a number of green options to their office fit-out."