Based on figures from the Central Statistical Agency in 2005, Welenchiti has an estimated total population of 20,984 of whom 10,545 were males and 10,439 were females. The 1994 national census reported this town had a total population of 11,732 of whom 5,719 were males and 6,013 were females.
In June 1995, Welenchiti experienced violence between the Ethiopian Orthodox and Protestant churches. Priests of the Ethiopian Church had prohibited Protestants to use its cemetery to bury their dead. In the resulting violence, a gas station owned by Protestants was destroyed.