The short but sweet note from Dylan Thomas to wife Caitlin, scribbled on the back of a bank stub, will be returned to Swansea thanks to Â£935,700 from the Heritage Lottery Fund (HLF).
The Dylan Thomas Centre is being expanded so more treasures can be seen.
It is all part of the celebrations marking the centenary of his birth.
The love letter is addressed to "My darling own dear dear Cat" and apologises that cheques the poet had sent her are late because work commitments prevented him from getting to the bank.
It was later sold by Thomas in 1941 to the University of Buffalo in New York.
Money from the HLF will ensure that the new look exhibition will be opened in time to mark the centenary of Thomas' birthday in October.
The grant will also allow the Grade II-listed building to show significantly more than 950 artefacts while an education and multimedia audio and video suite will also be created.
Thomas' granddaughter Hannah Ellis, who has played a key role in the project, said: "The centre is home to the largest collection of Dylan Thomas-related material in the world, a collection that provides a unique insight into who my grandfather truly was.
"I want young and new audiences to be able to learn about and discover my grandfather's poems, his stories and his plays. This grant from the HLF will bring the exhibition into the 21st Century and open it up for future generations to enjoy."
The poet, whose work includes Do Not Go Gentle Into That Good Night and the play Under Milk Wood, died in 1953 aged 39.
Former president of the United States Jimmy Carter, a devoted fan of Thomas, said: "Dylan Thomas was one of the greatest poets of the past century and I have always felt an affinity to his poetry and literature.
"I have continuously advocated the importance of commemorating his life and work and having first opened this important centre in Swansea, it is great to see that this funding will ensure that the Dylan Thomas Centre can continue to thrive in years to come."
A rarely seen love letter written by Wales' most famous poet will be displayed in his hometown for the first time.