Barangay Kasilawan belongs to the Makati City's first district, and is a member of the Northwest Cluster or Cluster 3 of Makati. Kasilawan is the smallest barangay in Makati with a total land area of only 0.946 square kilometers. that is 0.30% of the total land area of Makati. Based on its existing land use, Kasilawan is predominantly a residential area.
During the 2010 NSO census, its total population is 5,291 which is lower than the 2007 data which is 5,756. Relating this to its total land area, there are 56 residents per 1,000 square meters.
Although relatively a small barangay, the residence of the first Mayor of Makati, Mayor Pablo Cortez is located in barangay Kasilawan.