Loynes will start as MD for tech in January, replacing Grant Currie, who is heading to Porter Novelli.
The move follows five years at Chameleon, including being awarded the PRCA’s Agency Head of the Year prize in 2011.
Before this he was the EMEA PR director for Cambridge Technology Partners and Novell. He has also worked at agencies including Edelman and Text 100, handling clients including BT, Citrix, Hitachi, Microsoft, Motorola and Orange.
Richard Millar, president and CEO of H+K Strategies UK and Europe, praised Loynes' "outstanding leadership and team-building skills".
"I know his creativity and strategic thinking will become a valuable asset to our clients and team," he added.
It is understood that following the arrival of Tom Berry at Chameleon as CEO there will be no direct replacement for the MD role.