The Central District of Semnan County () is in Semnan province, Iran. Its capital is the city of Semnan.
At the time of the 2006 National Census, the district's population was 135,872 in 39,101 households. The following census in 2011 counted 167,407 people in 48,518 households. The 2016 census recorded the district's population as 196,521 inhabitants in 52,011 households.