East Butler is a borough in Butler County, Pennsylvania, United States. The population was 732 at the 2010 census. East Butler is located east of the center of Butler County at 40°52′40″N 79°50′38″W / 40.87778°N 79.84389°W, in the valley of Bonnie Brook, a tributary of Connoquenessing Creek. It is 3 miles east of downtown Butler, the c…East Butler is a borough in Butler County, Pennsylvania, United States. The population was 732 at the 2010 census. East Butler is located east of the center of Butler County at 40°52′40″N 79°50′38″W / 40.87778°N 79.84389°W, in the valley of Bonnie Brook, a tributary of Connoquenessing Creek. It is 3 miles east of downtown Butler, the county seat.