OpenAI chief executive Sam Altman said the move was an "opportunity to attract world-class talent".
It comes after he criticised the EU's proposed legislation regulating artificial intelligence (AI), which would require companies to reveal the content used to train their systems.
The UK meanwhile is planning what it calls "pro-innovation" regulation.
"We are thrilled to extend our research and development footprint into London, a city globally renowned for its rich culture and exceptional talent pool," said Diane Yoon, OpenAI VP of People.
"We are eager to build dynamic teams in research [and] engineering... to reinforce our efforts in creating and promoting safe AI."
When ChatGPT burst onto the scene last November, the chatbot's ability to give human-sounding answers to questions kickstarted intense global interest in the latest AI-powered products.
It also sparked a debate about what threats AI potentially poses - and what regulation is needed to mitigate those risks.
At an event at University College London in May, Mr Altman said he believed AI could create jobs and reduce inequality.
Prime Minister Rishi Sunak said at the event that AI could "positively transform humanity" and "deliver better outcomes for the British public, with emerging opportunities in a range of areas to improve public services".
ChatGPT has proven controversial, being briefly banned in Italy before it was restored in April 2023.
The UK government said it has invested £2.5bn in AI since 2014.
The BBC has approached the Department for Science, Innovation and Technology for comment.