In order for Oporto British School to maintain the highest standards in all areas of school life and to help the School to continue on a path of continual improvement, it is inspected or accredited by various Portuguese, British and international entities. OBS is a fully accredited member of the Council of International School (CIS), the Council of British International Schools (COBIS), the International Baccalaureate (IB), and is inspected by the Inspeção-Geral da Educação e Ciência (IGEC) as well as the Independent Schools Inspectorate (ISI).

Through COBIS, OBS underwent an ISI (Independent Schools Inspectorate) inspection in March 2013 and 2018, and more recently in October 2021. OBS is the only school in Portugal with this inspection status and as such is the only school recognised by the Department for Education of the United Kingdom.

OBS was first accredited by the Council of International Schools (CIS) in 2005. The School has since been reaccredited in 2016 and is currently in the process of preparing for a re-accreditation visit. OBS was the first school in Northen Portugal to achieve a full CIS accreditation.

OBS is an accredited member of COBIS (Council of British International Schools), that represents over 450 schools and organisations in more than 80 countries across the world.

OBS joined the The Independent Association of Prep Schools (IAPS) in 2014, which has over 660 of the world’s leading prep schools in membership.

OBS is an IB school which has delivered the IB Diploma Programme since 1992.

Within the framework of the Organisation and Functioning of the Private Schools in Portugal, OBS was inspected by the Inspeção Geral de Educação e Ciência in 2019.