Boyle, who has run APAC since 2016, becomes chief executive of Publicis Media EMEA and APAC in his expanded role.
Nicole Pruesse, who has been chief operating officer of EMEA since 2016, takes a similar expanded role as chief operating officer of Publicis Media EMEA and APAC.
Boyle, who is Scottish, and Pruesse, who is German, will be in charge of all of Publicis Media’s global operations outside the Americas.
Publicis Media said a "unified leadership structure" across EMEA and APAC will help in "simplifying" the business and improving "service" for clients.
Boyle and Pruesse are both veterans of Zenith Optimedia – like Steve King, the global chief executive of Publicis Media, and Tim Jones, the chief executive of Publicis Media Americas.
King broke up Zenith Optimedia and sister unit Starcom Mediavest Group into four agencies in a single operating unit, Publicis Media, in 2016 as part of a group-wide restructuring.
"This is a further step in strengthening and simplifying Publicis Media," King said, referring to the decision to merge the leadership of EMEA and APAC two years after first setting up the operating company.
"Simplicity of management is the attraction. It just makes it easier for EMEA and APAC to be under one leadership."
Boyle, who is based in Singapore, will split his time between Asia and Europe until the end of the year when he will move back to the UK.
King said: "Gerry is a proven and well-known leader, strategist and client partner."
Boyle assumes the responsibilities previously held by Iain Jacob, who has stepped down as chief executive of EMEA.
King said he has tried to promote an even balance of executives from Zenith Optimedia and SMG in Publicis Media - just as he did when he merged Zenith and Optimedia a decade and a half ago.
He pointed out that agency CEO roles are not the only important positions within Publicis Media and client leadership jobs carry increasing weight.
"We're clearly moving to a world where it's about client-centric solutions and they're going to be delivered through agency brands," he said.
Publicis Media, which includes Blue 449, Performics, Spark Foundry, Starcom and Zenith, is marking its second anniversary .
It has expanded from around 18,000 to 24,000 staff over the period, partly through the addition of Digitas.
"Having one P&L in each market is probably the best thing we did because the agencies work together, instead of competing," King said.
Publicis Groupe needs to cut costs after promising shareholders at its investor day in London in March that it would improve operating margin by 0.3% to 0.5% per year between 2018 and 2020.