In 1969 the municipality got its present size when "old" Lerum was amalgamated with Skallsjö and Stora Lundby.
In 2007, Lerum Municipality launched a new logotype to used instead of its official municipal coat of arms which features the head of an ox and three oak leaves. Municipal officials and PR staff felt the coat "outdated". Although no longer used, the coat of arms still has official status. The new logotype features a multi-coloured weaving pattern.