# List of Security and Investigations companies in New York

Tamtam tracks 25 Security and Investigations companies headquartered in New York. This list ranks all of them by number of employees on LinkedIn, led by Guardsmark, UNDSS and Mulligan Security. Their median headcount is 183. Half of them were founded in 2000 or later.

These New York-based security and investigations companies primarily offer a range of services from on-site security personnel to advanced technological solutions. Many specialize in protecting corporate facilities, critical infrastructure, and high-profile individuals. Guardsmark provides worldwide security services and investigations, while UNDSS focuses on safety and security for United Nations personnel globally. Mulligan Security supplies fire safety and security professionals for commercial buildings. MSA Security offers canine detection teams and X-ray technology to mitigate threats.

The companies listed show a strong concentration in providing comprehensive security solutions for businesses and organizations. Many of these firms, such as DGA Security, founded in 1969, and Silverseal, established in 1988, have long operational histories, indicating a mature market for security services in New York.

🇺🇸 New York · 25 companies · Updated Nov 15, 2026

| # | Company | Industry | Headquarters | Employees | Founded |
|---|---|---|---|---|---|
| 1 | [Guardsmark](https://www.tamtam.ai/c/guardsmark) (aus.com)<br>This company provides security services, investigations, consulting, facility design, and specialized services such as executive protection and background screening worldwide | Security and Investigations | 🇺🇸 New York | 1,343 |  |
| 2 | [UNDSS](https://www.tamtam.ai/c/undss) (un.org)<br>A department of the United Nations providing safety and security services globally for UN personnel, dependents, and premises | Security and Investigations | 🇺🇸 New York | 1,246 | 2005 |
| 3 | [Mulligan Security](https://www.tamtam.ai/c/mulligan-security) (aus.com)<br>Provider of top security and fire safety professionals for high-rise commercial buildings and corporate facilities, part of Protos Security for advanced services | Security and Investigations | 🇺🇸 New York | 854 | 1992 |
| 4 | [MSA Security](https://www.tamtam.ai/c/msa-security) (aus.com)<br>Provides innovative security solutions including canine detection teams and advanced X-ray technology to mitigate explosive and active shooter threats worldwide. | Security and Investigations | 🇺🇸 New York | 614 | 1987 |
| 5 | [Harvard Protection Services, LLC.](https://www.tamtam.ai/c/harvard-protection-services-llc) (harvardprotect.com)<br>A premier security firm offering comprehensive services including security, hospitality, and life safety personnel supported by state-of-the-art technology | Security and Investigations | 🇺🇸 New York | 424 | 1996 |
| 6 | [WSO Worldwide Security Options](https://www.tamtam.ai/c/wso-worldwide-security-options) (wso-security.com)<br>An international company specializing in strategic corporate security, providing innovative solutions to identify, control, and manage risks for businesses worldwide | Security and Investigations | 🇺🇸 New York | 272 | 2010 |
| 7 | [Security Guard Service](https://www.tamtam.ai/c/security-guard-service) (linkedin.com)<br>This company offers executive protection and security guard services in New York and nationwide, with 24/7 dispatch capabilities for immediate response | Security and Investigations | 🇺🇸 New York | 265 | 2008 |
| 8 | [MG - Mulligan Security](https://www.tamtam.ai/c/mg-mulligan-security) (aus.com)<br>Security professionals offer expert risk assessment and crisis management plans, conduct investigative due diligence, and provide training to help corporations mitigate risks and recover from crises efficiently | Security and Investigations | 🇺🇸 New York | 236 | 2008 |
| 9 | [DGA Security](https://www.tamtam.ai/c/dga-security) (dga.com)<br>A leading provider of business security solutions since 1969, offering intrusion alarms, video surveillance, access control, fire alarm systems, and more | Security and Investigations | 🇺🇸 New York | 223 | 1969 |
| 10 | [Excel Security Corporation](https://www.tamtam.ai/c/excel-security-corporation) (excelsecurity.com)<br>An internationally recognized security services provider offering personnel security, investigations, training, access control, surveillance installation, and emergency response since 1992 | Security and Investigations | 🇺🇸 New York | 199 | 1992 |
| 11 | [Silverseal](https://www.tamtam.ai/c/silverseal) (silverseal.net)<br>A global security solutions firm with experienced professionals offering a wide range of services including executive protection, investigations, and special event security | Security and Investigations | 🇺🇸 New York | 196 | 1988 |
| 12 | [CSS Security](https://www.tamtam.ai/c/css-security) (csssecurityservices.com)<br>A security company founded in 1975, providing high-level protection for various events, corporations, and individuals with professionally trained staff | Security and Investigations | 🇺🇸 New York | 192 |  |
| 13 | [ESCC](https://www.tamtam.ai/c/escc) (escc.com)<br>A leading provider of integrated security and communications solutions for commercial properties, residential properties, and development projects for over 30 years | Security and Investigations | 🇺🇸 New York | 183 | 1985 |
| 14 | [Stroz Friedberg, a LevelBlue company](https://www.tamtam.ai/c/stroz-friedberg-a-levelblue-company) (aon.com)<br>Specialized risk management firm focusing on cybersecurity, digital forensics, incident response, eDiscovery, and due diligence to help organizations address complex challenges | Security and Investigations | 🇺🇸 New York | 178 | 2000 |
| 15 | [Narrow Security](https://www.tamtam.ai/c/narrow-security) (narrowsecurity.com)<br>This company based in New York offers Fire Guard and Security Guard Services nationwide to residential, commercial, and private clients, ensuring safety around the clock | Security and Investigations | 🇺🇸 New York | 172 | 2014 |
| 16 | [Private Investigator](https://www.tamtam.ai/c/private-investigator) (privateinvestigatorweb.com)<br>The company provides services such as background checks, due diligence reports, and investigations to help clients make informed decisions and reduce risk exposure | Security and Investigations | 🇺🇸 New York | 152 | 2000 |
| 17 | [Beau Dietl & Associates](https://www.tamtam.ai/c/beau-dietl-and-associates) (investigations.com)<br>Premier private investigation firm with offices across the US and global partners Specializing in thorough investigations, security, and exceptional communication | Security and Investigations | 🇺🇸 New York | 147 | 1985 |
| 18 | [Alliance Security US](https://www.tamtam.ai/c/alliance-security-us) (alliance.us)<br>Integrated security and technology company in NYC, providing physical security and technology solutions for businesses to create safe and secure environments | Security and Investigations | 🇺🇸 New York | 68 | 1992 |
| 19 | [Unity Building Security](https://www.tamtam.ai/c/unity-building-security) (unitybuildingsecurity.com)<br>A leader in top-tier security services with specialized solutions for property managers, corporations, retailers, event organizers, and cultural institutions | Security and Investigations | 🇺🇸 New York | 36 | 1996 |
| 20 | [Polaris Corporate Risk Management](https://www.tamtam.ai/c/polaris-corporate-risk-management) (polarisrsk.com)<br>With over 50 years of experience, Polaris excels in corporate risk management, offering Crisis Management, Investigations, Protective Services, Travel Security, and Global Intelligence solutions | Security and Investigations | 🇺🇸 New York | 36 |  |
| 21 | [Reliant Safety](https://www.tamtam.ai/c/reliant-safety) (reliantsafety.com)<br>A subsidiary providing property security and management solutions for affordable housing nationwide through innovative technologies and highly-trained personnel | Security and Investigations | 🇺🇸 New York | 35 | 2009 |
| 22 | [DeLuca Advisory Services](https://www.tamtam.ai/c/deluca-advisory-services) (delucaadvisory.com)<br>Specialists in law enforcement, risk management, and compliance offering tailored solutions to protect reputation and assets for clients of all sizes | Security and Investigations | 🇺🇸 New York | 33 | 2019 |
| 23 | [RSAT Security Consulting](https://www.tamtam.ai/c/rsat-security-consulting) (rsatsecurity.com)<br>RSAT Security Consulting provides top-tier security and executive protection training and operations solutions to government and private sectors globally | Security and Investigations | 🇺🇸 New York | 10 |  |
| 24 | [Investigative Management Group](https://www.tamtam.ai/c/investigative-management-group) (investigativemanagement.com)<br>A leading provider of corporate security and intelligence services based in New York City, offering services to large corporations, financial institutions, law firms, and high-net-worth individuals globally | Security and Investigations | 🇺🇸 New York | 10 | 2003 |
| 25 | [The NY Locksmith](https://www.tamtam.ai/c/the-ny-locksmith) (thenylocksmith.com)<br>A NYC-based locksmith and security systems company specializing in Access Control, Surveillance, Communications, and advanced security solutions bridging the present to the future | Security and Investigations | 🇺🇸 New York | 3 | 2015 |

## How this list is built

Every company on this list has a Tamtam company profile. The industry is the one the company gives on LinkedIn; categories such as SaaS or fintech are classified by Tamtam's AI from the company's website and LinkedIn page; and the headquarters city must match the company's own address. Companies are ranked by the number of employees on LinkedIn, and the list is refreshed every night. Classifications can be wrong, so treat the list as a starting point rather than an official ranking. Last updated Nov 15, 2026.

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## The same list elsewhere in United States

- [Security and Investigations companies in the United States](https://www.tamtam.ai/l/security-and-investigations-companies-united-states) (288)
- [Security and Investigations companies in New York State](https://www.tamtam.ai/l/security-and-investigations-companies-new-york-state) (47)
- [Security and Investigations companies in California](https://www.tamtam.ai/l/security-and-investigations-companies-california) (36)
- [Security and Investigations companies in Florida](https://www.tamtam.ai/l/security-and-investigations-companies-florida) (25)

## The same list elsewhere

- [Security and Investigations companies in North America](https://www.tamtam.ai/l/security-and-investigations-companies-in-north-america) (352)

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Source: https://www.tamtam.ai/l/security-and-investigations-companies-new-york