The group said Ioannou's appointment would further strengthen its presence across two of its "most strategically important" international markets.
Ioannou brings more than a decade of industry experience from working in the Greek and wider Mediterranean hospitality sector, during which time he has built expertise in business development, strategic account management and market growth.
In his new role with Mayor, Ioannou will work closely with agents, operators, travel trade professionals and distribution partners to develop new strategic partnerships.
He will also work towards bolstering Mayor's presence in the UK and Irish market, strengthening partner engagement and delivering commercial strategies.
Ioannou said he was pleased to join a group that shares his passion for authentic hospitality, guest experiences and meaningful partnerships.
"The collection offers a distinctive blend of luxury, character and genuine Greek hospitality, and I look forward to working closely with our partners across the UK and Ireland to showcase these exceptional properties and contribute to the continued success and growth of the brand."
Mayor Hotels & Resorts operates three properties on the island of Corfu – Cabo, a contemporary adults-only all-inclusive retreat located in the south of the island; Unda, an adults-oriented experience featuring modern design; and Restia, a refined beachfront property offering personalised service.
Elena Anthi, Sales and Marketing Director at Mayor Hospitality Management, said Ioannou would play an important role "cultivating relationships with tour operators, travel advisors, trade partners and other strategic stakeholders".
"We look forward to the expertise, energy and commitment he brings as we continue to elevate the Mayor Hotels & Resorts brand."
Spirella Linardou, Chief Executive of Mayor Hospitality Management, said Ioannou joined the business at an exciting time, "bringing valuable market insight, commercial expertise and a relationship-driven approach".
"His strong understanding of international hospitality distribution, combined with his ability to build lasting partnerships across tour operators, travel advisors and the wider travel eco-system, will be instrumental in supporting our growth ambitions in the UK and Irish markets."