The law seeks to standardise the service, which is in high demand.
There will be a commission, chaired by the national police chief, to regulate the industry.
Under the law, security service operators need to obtain a four-year licence. Over half of their directors must be Thai.
Security guards also need to obtain a licence and must not have a prison record.
Violators of the law face more than one year of jail or a fine of up to Bt 100,000.