The ceremony starts at midday (UK time) at St George's Chapel, Windsor Castle.
The American TV actress' family has been in the news for their controversial statements about the bride-to-be.
As the Christian customary, Meghan's father was to walk her down the aisle on her D-day. She said reporters had also harassed him at his home and that he recently suffered a heart attack. His absence is a result of a revelation that he posed for the paparazzi in a staged photo outside his house in Mexico.
His daughter Samantha Markle, Meghan's half sister from whom she is estranged, said on Twitter yesterday that the staged shots were her idea in a bid to create a more positive public image for their father.
Kensington Palace issued a statement calling for "understanding and respect to be extended to Mr. Markle in this hard situation".
A composite photo showing Meghan Markle and her father, Thomas.
The report also mentions that Markle is back in the hospital after reportedly being treated for a heart attack a week ago.
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Meghan is Doria's only child, and the two are known to have a close relationship, with Doria accompanying Meghan on the red carpet on many occasions and even attending the Invictus Games with Meghan and Harry previous year. "It was an unbelievable amount of stress - by his report they were stabilising him", she said.
The couple took the unusual step of issuing a statement last night after former Hollywood lighting director Thomas Markle revealed he would be staying away from the wedding on Saturday to spare his daughter any further embarassment.
"They [doctors] will go in and clear blockage, fix damage and put a stent where it is needed", Thomas told TMZ of the operation.
Thomas Markle and Ragland divorced when their daughter was 6-years-old, but they both played an active role raising her.
He said that if doctors allow him to be discharged, he will fly to London. After that, Thomas Markle would have a cup of tea with his new in-laws.
"Diana turned the royal family inside out", said Ellis Cashmore, honorary professor of sociology at Aston University and author of books on celebrity culture.
Dooley and her sons, who live in OR, previously said they had not seen Markle in 20 years and had not received an invitation to the royal wedding. He feels that anyone who gets associated with his life - this is the price they have to pay.