The Wellington Infantry Regiment was a military unit of the New Zealand Expeditionary Force (NZEF) raised for service in the First World War. It saw service in the Gallipoli Campaign (1915) and on the Western Front (1916–1919). The regiment was formed by grouping together companies from four different territorial regiments base in the Wellington Military district.

The New Zealand Expeditionary Force (NZEF) was the title of the military forces sent from New Zealand to fight alongside other British Empire and Dominion troops during World War I (1914–1918) and World War II (1939–1945). Ultimately, the NZEF of World War I became known as the First New Zealand Expeditionary Force. The NZEF of World War II was known as the Second New Zealand Expeditionary Force (2NZEF).