Allied Universal is an American private security and staffing company.

Formed in 2016 by the merger of AlliedBarton and Universal Services of America, Allied Universal is the world's largest provider of security guards.

It is also the third largest United States–based employer globally.With the 2022 acquisition of Attenti Group , one of the world's leading electronic monitoring companies.

Allied Universal will integrate Attenti Group with G4S Monitoring Technologies, to create Allied Universal Electronic Monitoring Services.

The combined business has pro-forma 2021 revenues over $150m with operations in more than 35 countries, and will establish Allied Universal Electronic Monitoring Services as a global market leader in electronic monitoring solutions.