He is a senior partner in Chesapeake Strategies Ltd, advising organizations on innovations in the building, design, security, and urban sectors.

During his work with Brooks Stevens, Vonier developed skills in sketching, mechanical drawing, modelmaking, shop techniques, and illustration.

As a graduate student in architecture, Vonier received a fellowship from the National Science Foundation to study museum design.

Based in Paris and Washington D.C., Vonier's practice serves public and private clients with global industrial operations.

As a board certified security professional, Vonier led groundbreaking research for US embassies and consulates, resulting in landmark recommendations to the Secretary of State and a new generation of design criteria.

He received the Henry Adams Award for his research on public museums, completed under a fellowship from the National Science Foundation.

He was elected to serve as Secretary General of the International Union of Architects (UIA)[4] in Paris, and leads in its roles with UNESCO, the WTO and various world heritage and climate organizations.

Vonier was senior security advisor for overseas operations and facilities to the Halliburton corporation, reporting directly to its chief executive, Dick Cheney.

He led multiple "red team" exercises, conducted post-incident analyses, and designed security upgrades for sites operated worldwide by Halliburton and its subsidiary, Brown & Root.

He led evaluations of NATO operational sites and billeting facilities, and assessments of field offices and oilfield worksites in Eastern Europe, Eurasia, and North Africa.

He worked with the Rand Corporation on comparative municipal security studies in the aftermath of motor vehicle attacks in Nice, New York, and Barcelona.

In addition to the US Department of State and the National Park Service, his firm has worked for UN-ESCAP, Butler Manufacturing (now Bluesteel), the City of Yokohama, and multiple private corporations.

Vonier served for fifteen years as the European correspondent for Progressive Architecture magazine, and the industry nominated his "Technics" articles for the Jesse H. Neal Award.

Shortly after establishing his office in Paris, France, Vonier founded AIA Continental Europe, chartered in 1994 as an offshore chapter of the American Institute of Architects, with members from Ireland to Russia and from Turkey to Finland.

At the AIA Conference on Architecture in Orlando, Florida, Vonier interviewed former First Lady Michelle Obama, his invited guest, in front of more than ten thousand people.

From the UIA's headquarters in Paris, Vonier led in renewing the organisation's work with UNESCO, UN Habitat, and other international heritage and design institutions.

With Edward Larrabee Barnes as lead architect, Vonier was part of the team to win a P/A Design Award for the College of the Atlantic in Bar Harbour, Maine.

He received the Henry Adams Award for Excellence in Architecture for graduate research on public museums, funded by the National Science Foundation.