Santhia () is an upazila of Pabna District in the Division of Rajshahi, Bangladesh.
Santhia is located at . It has 89,032 households and a total area of 331.55 km<sup>2</sup>. Santhia has some forest-like areas with wild animals like foxes, mongooses, wild cats, etc. But these woods and animals are on the verge of extinction because of hunting and slash-and-burn.
According to the 2022 Bangladeshi census, Santhia Upazila had 105,951 households and a population of 410,767. 9.20% of the population were under 5 years of age. Santhia had a literacy rate (age 7 and over) of 67.37%: 68.23% for males and 66.53% for females, and a sex ratio of 98.57 males for every 100 females. 59,897 (14.58%) lived in urban areas.
According to the 2011 Census of Bangladesh, Santhia Upazila had 89,032 households and a population of 380,301. 88,808 (23.35%) were under 10 years of age. Santhia had a literacy rate (age 7 and over) of 43.88%, compared to the national average of 51.8%, and a sex ratio of 989 females per 1000 males. 38,704 (10.18%) lived in urban areas.
As of the 1991 Bangladesh census, Santhia has a population of 283,463. Males constitute 52.2% of the population, and females 47.8%. This Upazila's eighteen up population is 135,476.
Santhia Upazila is divided into Santhia Municipality and ten union parishads: Ataikola, Bhulbaria, Dhopadaha, Dhulauri, Gourigram, Karanja, Kashinathpur, Khatupara, Nagdemra, and Nandanpur. The union parishads are subdivided into 176 mauzas and 234 villages.
Santhia Municipality is subdivided into 9 wards and 27 mahallas.
Chairman: 01. Abdullah Al Mahmud Deloar
Vice Chairman: 01.Md Khokon
Woman Vice Chairman: 01. Selima Rahman Shila
Upazila Nirbahi Officer (UNO): Md. Abdur Razzaque Sarker https://web.archive.org/web/20120226125127/http://www.moestab.gov.bd/pmis/Forms/unolist.php Dr. Md. Aminul Islam Nasim, Physician
Municipality:
Chairman: Mahbubul Alam Bacchu
Councillors: Md. Abdul Awoal Md. Saiful Alam Md. Shirajul Islam Md. Daud