Allied Security was originally founded under the name Allied Barton Security in 1957. In 1965, the name was changed to Universal Protection. Over the years, the company has been acquired or has acquired a long list of security companies.
In 2016, AlliedBarton and Universal Services of America merged, renaming the company Allied Universal Services. After this merger, Allied Universal became the largest security company in the US.
In 2019, the company expanded internationally by opening offices in the UK.
In December 2019, the company was hit with a ransomware demand from Maze Crew. Maze Crew did make some information public in early 2020 after Allied refused to pay the ransom.
Allied Universal Security maintains a corporate office in Conshohocken, Pennslyvania.