From the Wikipedia page 
Kiev Oblast or Kyiv Oblast (Ukrainian: Київська область, translit. Kyivs’ka oblast’; also referred to as Kyivshchyna – Ukrainian: Київщина) is an oblast (province) in central Ukraine. The administrative center of the oblast is the city of Kiev (Ukrainian: Київ, Kyiv), which also serves as the capital of Ukraine. Despite being located in the center of the Kyiv Oblast, and hosting the governing bodies of the oblast, Kyiv itself is a self-governing city with special status and not under oblast jurisdiction.
Kyiv Oblast neither corresponds to nor is limited to the unofficially designated Kiev metropolitan area although it is significantly dependent on the urban economy and transportation of the latter.
The largest city in the oblast is Bila Tserkva.
The Chernobyl Exclusion Zone is technically located within the northernmost part of the Kyiv Oblast but access to the Zone is prohibited to the public and it is administered separately from the oblast.