County Councillors, Aldermen and distinguished guests including Lord Lieutenant, Sir Henry Aubrey-Fletcher Bt, KCVO and High Sheriff, Mrs Julia Upton MBE packed into the Oculus in Aylesbury to mark the historical occasion.
The County Council and Buckinghamshire's four district councils are being replaced by the new unitary Buckinghamshire Council on 1 April.
Alongside regular meeting business, councillors took the opportunity to look back over Council services spanning three centuries. Over this time, average life expectancy in the County has risen from just 46 in 1889 to over 81 currently, and population has nearly trebled to 540,000.
The last ever Chairman of Buckinghamshire County Council, Brian Roberts, said he was proud of being given the privilege of ending such a historic chapter.
Councillor Roberts said: "This Council has been serving Buckinghamshire residents since 1889. During that time we've seen four Monarchs, 26 prime ministers and 32 County Chairman.
“The decisions made by both our current and predecessor councillors have shaped how Buckinghamshire has developed as a County and how services have contributed to making life better for residents, businesses and communities.
"The County and the four districts councils now pass the baton on to Buckinghamshire Council and I wish the new authority every success going forward.”