The ceremony will be attended by 1,000 common people who were chosen after a public lottery.
The physicist's voice - set to a piece by Greek electronic music composer Vangelis, who created the soundtrack for the 1981 film Chariots of Fire - was sent from the European Space Agency's Cebreros station in Spain.
Stephen Hawking has taken his place among Britain's greatest scientists with the burial of his ashes in Westminster Abbey, between the graves of Charles Darwin and Isaac Newton.
Kip Thorne, a Nobel prize-winning American physicist, paid tribute to "by far the most stubborn friend I ever had".
A black slate memorial stone lies above, bearing the inscription: "Here lies what was mortal of Stephen Hawking 1942 - 2018".
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Hawking conducted groundbreaking research into black holes and the origins of the universe, and gained global fame as a popularizer and communicator of science.
The famed cosmologist, who passed away in March at the age of 76, always dreamed of flying to space, and now, his voice is is on a journey through the cosmos.
Interment inside Westminster Abbey is a rarely bestowed honour.
In 1963, shorty before his 21st birthday, Hawking was diagnosed with amyotrophic lateral sclerosis, a neuro-degenerative disease, and although he required a wheelchair and a speech synthesizer, Hawking lived for many years beyond the prognosis.
One of Hawking's major theories was that black holes can shrink or evaporate as they allow radiation to escape.
His book, A Brief History Of Time, sold 10 million copies and was translated into 40 different languages.
"I'm going to be an actress; everybody who puts their mind to something gets to be it. Stephen Hawking proved that more than anyone".