The Friday afternoon saw readings given by top names such as astronaut Tim Peake, astronomer Martin Reece and Hawking's collaborator and Nobel prize victor Kip Thorn.
Other people who spoke at Hawking's internment include actor Benedict Cumberbatch, who portrayed Hawking in a TV show; Hawking's daughter Lucy; astronaut Tim Peake, who read from Percy Bysshe Shelley's Queen Mab; and Nobel Prize victor Kip Thorne, who described Hawking as "the most stubborn friend" that he has ever had.
Lucy said: "The broadcast will be beamed towards the nearest black hole, 1A 0620-00, which lives in a binary system with a fairly ordinary orange dwarf star".
Afterwards his recorded voice, set to a special piece of music, was beamed into space into a black hole light years away as "a message of peace and hope".
The physicist's voice set to a piece by Greek electronic music composer Vangelis was broadcast by the European Space Agency later on Friday. One of the equations devised by Hawking, describing the entropy of black holes, was also inscribed on his stone.
Many considered Hawking to be the greatest scientist of his generation, overcoming a debilitating disease to gain a worldwide following for his brilliant work in theoretical physics.
Undaunted, he defied his prognosis by decades - pursuing his research at Cambridge while communicating through computerized speech, astonishing even himself, as he once told "60 Minutes": "For me, it is quite an achievement". An address was given by Astronomer Royal Martin Rees, who first met Prof Hawking at the University of Cambridge in the early '60s, while Prof Hawking's collaborator and Nobel prize victor Kip Thorne also gave a tribute.
Pau Figueras, a post-doctoral student who followed in Hawking's footsteps by studying black holes at the University of Cambridge eight years ago, said he believed Hawking's legacy "will live forever". Nobody else since Einstein has done more to deepen our understanding of space, time and gravity.
"It is a message of peace and hope, about unity and the need for us to live together in harmony on this planet", she said.
In 1986, he wrote "A Brief History of Time", an global bestseller which made him one of the most prominent names in science since Albert Einstein.
Westminster Abbey will also be open to the public free of charge after the service so people can pay their respects at his grave.
"We are so grateful to Westminster Abbey for offering us the privilege of a Service of Thanksgiving for the extraordinary life of our father and for giving him such a distinguished final resting place", Hawking's children had said earlier in a statement.