Gujarati, Marathi, Punjabi and Telugu will add to the Hindi, Urdu, Tamil and Bengali language services already being used by the news broadcaster.
"This is a historic day for the BBC, as we announce the biggest expansion of the World Service since the 1940s," said BBC director general Tony Hall.
"The BBC World Service is a jewel in the crown - for the BBC and for Britain. As we move towards our centenary, my vision is of a confident, outward-looking BBC which brings the best of our independent, impartial journalism and world-class entertainment to half a billion people around the world.
Today is a key step towards that aim," he said. The expansion is a result of a funding boost announced by the UK government last year. Other new languages to be added will include African languages of Afaan Oromo, Amharic, Tigrinya, Igbo, Pidgin and Yoruba as well as Korean.
The first new services are expected to launch by next year. The plans also include the expansion of BBC's digital services to offer more mobile and video content and a greater social media presence.
The BBC also launched a full digital service in Thai, following the success of a Facebook-only "pop-up" service launched in 2014. The new language services mean the BBC World Service will be available in 40 languages, including English, up from the current 29 languages.
Hall has set a target for the BBC to reach 500 million people worldwide by its centenary in 2022, up from the current 246 million.