Araihazar () is an upazila (sub-district) of the Narayanganj District in Bangladesh, part of the Dhaka Division.
Araihazar is named after the leftover 2,500 Mughal soldiers of Man Singh I that fought with Isa Khan in the 17th century. The word for "two thousand and five hundred" in Bangla is "Araihazar" ( romanised: Araihajar), hence the name.
In 1921, a thana (police outpost administrative headquarters) was established in Araihazar, under the former Dhaka district. Araihazar Thana's status was upgraded to upazila (sub-district) in 1983 as part of the President of Bangladesh Hussain Muhammad Ershad's decentralisation programme.
Araihazar is located at . It has 111,040 households and total area 181.07 km.
According to the 2022 Bangladeshi census, Araihazar Upazila had 111,021 households and a population of 467,547. 10.27% of the population were under 5 years of age. Araihazar had a literacy rate (age 7 and over) of 69.34%: 70.73% for males and 67.95% for females, and a sex ratio of 99.85 males for every 100 females. 90,937 (19.45%) lived in urban areas.
According to the 2011 Census of Bangladesh, Araihazar Upazila had 77,462 households and a population of 376,550. 96,076 (25.51%) were under 10 years of age. Araihazar had a literacy rate (age 7 and over) of 41.0%, compared to the national average of 51.8%, and a sex ratio of 999 females per 1000 males. 14,423 (3.83%) lived in urban areas.
As of the 2001 Bangladesh census, Araihazar has a population of 331566. Males constitute 51.75% of the population, and females 48.25%. This Upazila's eighteen up population is 142883. Araihazar has an average literacy rate of 32% (7+ years), and the national average of 32.4% literate.
Araihazar Upazila is divided into Araihazar Municipality, Gopaldi Municipality, and 11 union parishads: Bishnandi, Brahmandi, Duptara, Fatepur, Haizadi, Kalapaharia, Khagakanda, Mahmudpur, Sadasardi, Satgram, and Uchitpur.