The new outlet, known as Legal & General Insurance, will headed up by Bernie Hickman, who became L&G home finance chief executive and individual retirement managing director in 2014, having held several roles at the company including UK protection managing director, group financial controller, and investor relations director.
With over seven million customers in across both countries, the unit will offer life insurance, critical illness cover and income protection across the UK and US, said L&G.
Legal & General America alone has more than one million life insurance customers, and $1.2bn (£968m) of gross written premium.
The insurer added it wants to grow the US business so it offers multiple products and uses technology in a similar way to the UK business.
Legal & General has already investment business LGIM and Legal & General Retirement (LGR) in the US. LGIM entered country with $18bn in funds in 2005 which has now grown to $133bn for over 180 clients.
Group chief executive Nigel Wilson said:"Bernie is a proven successful leader. Legal & General has two large successful international businesses, LGIM and LGR. We are now developing our third international business, our insurance business.”
Hickman added: “Technology is playing an ever-increasing role in all areas of the UK and US insurance markets, with digital marketing and straight-through processing becoming ever more important.
“It’s therefore a great opportunity and an exciting time to combine our UK and US expertise, technology and insights, to grow our existing businesses and establish new, digital insurance businesses in selected international markets.”