Naldanga Upazila () is a subdistrict of Natore District, within Rajshahi Division in northern Bangladesh. Naldanga was previously a union of Natore Upazila in Rajshahi Division of Bangladesh but, in a Government gazette published in May 2013, Naldanga was declared an upazila of Bangladesh. Naldanga contains Naldanga Municipality and has 5 unions: Bipra Belgharia, Brahmapur, Khajuria, Madhnagar and Piprul.
According to the 2022 Bangladeshi census, Naldanga Upazila had 37,504 households and a population of 135,318. 7.85% of the population were under 5 years of age. Naldanga had a literacy rate (age 7 and over) of 70.73%: 73.36% for males and 68.24% for females, and a sex ratio of 95.93 males for every 100 females. 11,602 (8.57%) lived in urban areas.
According to the 2011 Census of Bangladesh, Naldanga Upazila had 33,507 households and a population of 129,304. 24,305 (18.80%) were under 10 years of age. Naldanga had a literacy rate (age 7 and over) of 51.37%, compared to the national average of 51.8%, and a sex ratio of 1010 females per 1000 males. 10,266 (7.94%) lived in urban areas. Ethnic population was 1,352 (1.05%).
Naldanga upazila comprises five unions and 99 villages.