OpenAI CISO Matt Knight steps down after over five years at the company

Matt Knight, OpenAI’s vice president and chief information security officer (CISO), has announced his resignation after more than five years at the artificial intelligence company. Knight shared the news in a detailed post on social media platform X, reflecting on his time at OpenAI and the evolution of its security operations.

I shared this note with @OpenAI today. Onward! pic.twitter.com/2aOpryGHF6

— Matt Knight (@embeddedsec) January 26, 2026

Knight joined OpenAI in 2020 as its first-ever security hire, at a time when the organisation was still a small research-focused lab preparing to launch GPT-3 and an experimental application programming interface. Since then, OpenAI has grown into one of the world’s most influential AI platforms, serving hundreds of millions of users globally.

In his post, Knight highlighted how the company’s security program expanded alongside OpenAI’s rapid growth. He said the team built systems that now safeguard some of the most widely used and critical AI technologies in the world, emphasising that earning user trust was central to that effort.

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“Together, we built a security program that now protects a global platform trusted by hundreds of millions of users,” Knight wrote, adding that defining security standards for a new frontier of artificial intelligence was among the most meaningful aspects of his role.

In recent years, Knight also led security-focused product development and research at OpenAI. This work culminated in the launch of Aardvark, a security initiative aimed at using artificial intelligence to strengthen software defence and protection. Knight described Aardvark as a reflection of his belief that AI can play a transformative role in improving cybersecurity.

With the launch of Aardvark completed, Knight said the timing felt right to step away. He expressed confidence that both the security organisation and the product would continue to grow under new leadership.

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OpenAI chief executive officer Sam Altman acknowledged Knight’s contributions in a public response, thanking him for building what he described as a world-class security team and for playing a foundational role in OpenAI’s development.

Knight concluded his message by thanking colleagues across OpenAI, particularly members of the security team, and said he looks forward to exploring new ideas and opportunities in the future.