Christians had existed in northwestern Tanzania since about 1890, especially through the work of the Catholic "White Fathers". However, there were also Christians baptized in Uganda who met independently. The EMDOA/Bethel Mission established a station in Bukoba in 1910. The first World War made working impossible, missionaries were not able to resume their work until 1927. In the meantime, the Church of Uganda (Anglican) had supported the Christians. During World War 2, the Swedish Church Mission took over the work of the Bethelers.

In 1955 the church became independent. After the bishopric of the Swede Bengt Sundkler, Josiah Kibira was elected the first African bishop in 1964 - he was later also president of the Lutheran World Federation.

Today, the Northwest Diocese (NWD) has 141,459 members in 235 congregations with 114 pastors, 230 evangelists and 1,156 full-time staff. In 2006, the first two women were ordained as pastors.

The diocese operates an extensive training program for pastors, evangelists, church musicians and artisans at Ruhija Theological College.There are several diaconal institutions: A small center for the mentally handicapped and an orphanage in Ntoma. An important role is played by the extensive project for AIDS orphans and widows (Huyawa).The Northwest Diocese includes the larger hospitals in Ndolage and Izimbya with numerous smaller health stations (dispensaries). At the Ndolage hospital, a UEM employee works as a surgeon. A training center for doctors working under rural conditions is being established there.