O'brien Contracting Canada Limited
O'Connor Associates Environmental Inc.
O'doig Consulting Services Inc.
O'hara Protection Corp.
O'Sullivan Systems Consulting Ltd.
O'Wolfe Holdings Ltd.
O.i. Johnson Construction Ltd
O.r.i. Energy Inc.
O2 Planning + Design Inc.
O7 Networks Inc.
Oak Environmental Inc.
Oakminn Investors, Inc.
Oakmoor Capital Holdings Ltd.
Oaks Associated Career Training International Ltd.
Oakwest Corporation Limited
Oakwood Durham Investments Inc.
Oakwood Petroleums Limited
Oakwood Petroleums Ltd.
Oasis Energy Solutions Inc.
Objective Research and Evaluation Inc.