Leominster is a city in Worcester County, Massachusetts, United States. It is the second-largest city in Worcester County, with a population of 43,222 at the 2023 census. Leominster is located north of Worcester and northwest of Boston. Both Route 2 and Route 12 pass through Leominster. Interstate 190, Route 13, and Route 117 all have starting/ending points in Leominster.