It will be dedicated by the Dean of Westminster in September.
Dr John Rae (1813 - 1893) was born in Orphir on the Orkney mainland but spent much of his life exploring northern Canada having signed up with the Hudson Bay Company.
The doctor discovered the final part of the Northwest Passage, which many believe should have seen him remembered as one of the most important explorers of his time, rather than dying in relative obscurity.
However, his achievement was overshadowed by controversy when he reported on the fate of the lost expedition led by Sir John Franklin, an English naval officer.
Accounts from local Inuits he had recorded in 1854, suggested the crew members had resorted to cannibalism in a desperate bid to survive.
A campaign to discredit Rae was subsequently waged by Lady Franklin and others, including Charles Dickens, after he relayed these reports.
The memorial to Sir John Franklin in Westminster Abbey, describes him as "..the beloved chief of the gallant crews who perished with him in completing the discovery of the route that links the Atlantic and Pacific oceans." In 2009 Billy Connolly was in the Arctic Circle for a TV programme and said it was a "crime" that Rae was not credited with discovering the route.
John Rae is buried in the kirkyard of St Magnus' Cathedral, Kirkwall, and there is a memorial to him in the cathedral.
And last year a bronze statue of him was unveiled in Orkney's second town Stromness.
The Dean of Westminster, the Very Reverend Dr John Hall, said he had agreed to the memorial following discussions with the Secretary of State for Scotland Alistair Carmichael, MP for Orkney and Shetland.