The Dean is the most senior priest at Southwark Cathedral, the mother church of the Anglican Diocese of Southwark.
The Bishop of Southwark, Rt Revd Christopher Chessun, presided at the service of Choral Evensong on Sunday afternoon that included the installation of Dr Oakley as Dean and rector of the cathedral parish and St Hugh's Bermondsey.
Dr Oakley succeeds the Very Revd Andrew Nunn who retired earlier this year after 11 years as dean.
In his sermon Dr Oakley drew on words of 17th century bishop Lancelot Andrewes to set out a manifesto for the cathedral "to continue being a place that engages with what matters - what really matters - and do it in such a way that - plausibly, imaginatively - contributes to public life and debate.
"That partners with people: creatives and charities and schools and liveries and community leaders, residents, politicians, local government, business, those of world faiths and none. Any - any - who shares values of the common good, because this world badly needs some kindness."
Those who gave official greetings to the new Dean during the service included deputy lieutenant Lynn Cooper as the King's representative, and Cllr Michael Situ, Mayor of Southwark.
Representatives of both Cathedral School in Redcross Way and St Saviour's & St Olave's School at Bricklayers Arms also formally welcomed Dr Oakley.
Amir Eden of Living Bankside offered greetings on behalf of local residents and the Muslim community.
Southwark Cathedral's own choir of girls, boys and lay clerks were joined for the occasion by musicians from St John's College Cambridge where Dr Oakley was latterly Dean of Chapel.
Dr Oakley's previous roles include stints as a canon of St Paul's Cathedral, as Anglican chaplain in Copenhagen and as rector of St Paul's Covent Garden.
Ecumenical guests at Sunday's service included Fr Joseph Donkor, sub dean of Southwark's Roman Catholic cathedral of St George, who was among those leading the intercessions.