The Ministry of Defence will remove the need for Commonwealth citizens to have lived in the UK for five years before applying for service.
An extra 1,350 personnel from oversees are hoped to be enlisted to the the navy, army and air force every year.
The move comes as the armed forces struggle to recruit enough personnel to fill a shortfall in their ranks.
Applicants from nations including India, Australia, Canada and Fiji will be considered for all roles in the forces, without having lived in the UK.
Until now, they had to have resided in Britain for five years and their recruitment was capped at a maximum of 200 per year.
The army will begin the admissions from early next year, while the navy and RAF will startÂ the process immediately.