The PSNI and SIA investigators carried out inspections at four venues including pubs and clubs, checking eight door supervisors in central, east and south Belfast.
Of the eight door supervisors checked, three held no licence, two were found working on an expired licence and one was found working on a revoked licence.
Officers from the PSNI and SIA investigators will be conducting further enquiries into these men.
An additional two individuals will be questioned in relation to managing door supervisors without holding the necessary SIA licence.
It is a legal requirement for both frontline security operatives and those who deploy them to be SIA licensed.
SIA Head of Investigation Sharon Roberts said: "All of the offences detected were at premises using in-house security staff. I would urge all employers of security to check the licence status of their staff using the SIA's Register of Licence Holders accessible via the SIA website.
"It is important for the safety of the public that security staff are properly vetted, trained and licenced. We are committed to working with the PSNI to ensure regular checks are carried out and will be paying particular attention to those premises that use their own security."
Area Commander for East Belfast, Chief Inspector Mark McEwan said: "Officers assisted SIA investigators during this operation. Our main aim was to educate local door staff about the need to be licensed and ensure compliance with UK legislation designed to protect the public.
"We will continue to work alongside and assist the SIA in conducting checks on door staff and licensees in the future."